I just got back and a friend who is taking the exact same cruise and is also cost conscious asked me to give him all my lessons learned. I figured you all might benefit even if some of this information isn't strictly about cruising. I'm going to ask my travel companions to review it (first time in Hawaii and first time cruising) to see if they have anything to add.

Getting There And Getting Around

Air Fare
With Southwest now offering tickets to Hawaii, I expect the competitive market to drop prices across the board but unless you are fortunate enough to live on the west coast in a city with flights that fly direct, air fare can be pricey. I had to get 4 people there round-trip (2 from rural Maine, 1 from Louisville Kentucky and 1 from the Baltimore/D.C. area). I ended up signing up for the Chase Sapphire credit card (annual fee waived for the first year) and the Alaska Airlines credit card that gave me a buy one/take one sign up offer. My total air fare cost was $2400. Besides the credit card, there was no secret other than monitoring the prices as far in advance as possible to see what typical prices are and then striking when there was a decent sale. I would also mention following Scott's Cheap Flights on the off chance a deal becomes available for when you were already planning on traveling.
Ground Transportation
We flew into Waikiki on Tuesday (cruise started on Saturday) so I got a rental car through Autoslash. The total cost for a mid-size for 4 days was $176 and ended up being from Alamo. While I feel this was a good deal as I had four people, if you're not 100% sure you will need it - you can probably get by with an Uber, taxi or even a hop on/off bus (see excursions later). Many excursions had an option for hotel pickup/drop-off.
Probably the best deal I found was Star Taxi which only charged $25 for up to 4 people one-way to/from the cruise terminal and not much more for other locations. Call 1 hour before you need the service.
Parking
Parking is EXPENSIVE so be sure to do a lot of research if you plan on renting a vehicle.

Oahu

General In your mind, you have this idea of what Hawaii is going to be like. Oahu (specifically Honolulu/Waikiki) is not it. It is very over developed and crowded. Many places are run-down because investors have purchased the property but have chosen to wait until conditions are more favorable to develop. There is a very large homeless population in Hawaii overall but I was shocked by the number of shanty towns and abandoned vehicles doubling as homes I saw on Oahu.
Excursions

• Snorkel-Cruise-Swim-Dolphins-Turtles - highly recommended (hint: This excursion may be cheaper directly with the vendor Dolphins And You - if you buy the photos, you will have to go to their Waikiki office later to pick them up and they will offer you a 10% discount on merchandise at that time).
• Shark Dive - Unfortunately, this tour got canceled due to weather so I can't comment on it. Since it is on the north shore, the plan was to do an early morning adventure (when the water is calmest) and then spend the rest of the time exploring the beaches and surfers. (hints: You may be able to get this cheaper directly with the vendor North Shore Shark Adventures and if you drive, take one way to get there and another way to get back so you can experience more of the island).
• Sunset Cruise & Show - The people I was going with had never cruised before so this was to get their feet wet so to speak. It was nice but not spectacular. You may be able to get it cheaper directly through the vendor Star Of Honolulu. On Fridays, they offer an extra hour for a nominal fee upgrade which includes fireworks. I didn't see the fireworks myself but several people I talked to said they are put on by a hotel and aren't anything special. (hint: If you drive, they will validate your parking ticket and parking will only be $4 instead of $18).
• Waikiki Trolley Hop-On Hop-Off You can trade time for money and if you have time, this would be a much more cost effective solution to getting around and is very configurable (how many days of use, how many different lines, etc.)
• Polynesian Culture Center - I had the Ambassador Luau Package With Circle Island Tour of Oahu. Pickup was at 8:30 in the morning and drop off wasn't until after 10 PM so it is a long day. If you do this one I have several recommendations. First, take it early in the trip because it includes a multi-day pass so you can go back at no charge for 3 more days and the Circle Island tour allows you to see some areas you may want to explore on your own. Second, you don't get food until 6 PM so be sure to eat breakfast first and plan the rest of the time accordingly (bring snacks for instance). The only thing I was disappointed in was the Diamond Head didn't actually drive up to the crater. Update After the initial post, I was reminded by mashel2811 of a few things. The PCC is Mormon owned/operated which has pros/cons. On the downside, there is no alcohol on-site and things overall tend on the conservative side. Not that I have an issue with that but if you're looking for authenticity then this would represent Polynesia post Christian missionaries. On the upside, it is a huge facility that truly will allow you to experience many of the cultures besides just Hawaii. Also, regardless of how you feel about religion, the money taken in from PCC helps to sponsor many students education from all over Polynesia. I had nothing to compare the luau to but I have heard from several other people that there are much better options (the luau at PCC is optional). The Breath Of Life was awesome.
• Pearl Harbor (see the end of the cruise excursions)

Recommendations/Notes

• You probably want a beach other than Waikiki due to the number of people - Hanauma Bay looked awesome. If you do decide to stay in Waikiki, walking the coastline towards Diamond Head is a better choice for the beach instead of around all the hotels. This is because in Hawaii, beach access and water is considered a public service (free)
• What is and isn't expensive didn't make any sense. Eggs imported from the mainland were cheaper than eggs from Hawaii despite chickens EVERYWHERE but I was able to get a large jar of peanut butter for $1.89. The best place I found for groceries was Don Quijote and it had a free parking garage.
• Souvenirs were much cheaper on other islands
• It rains - almost daily - but not for long - don't let it fool you - WEAR sunscreen of at least SP50
• Hydrate more than usual - especially if you're drinking beer like me
• Updates From original post below
• You can get insanely discounted Pearl Harbor tickets from recreation.gov but they sell out in 5 minutes. Exactly 7am Hawaii time they sell tickets for the next day or for 2 months out. Nothing in between. I recommend having 2-3 people trying it simultaneous for different time slots. The early tickets sell faster. Then the bus ride anywhere is $2.50 each. When you board the bus ask for a transfer ticket. The transfer ticket is good for two more rides for the next 2.5 hours. If you get out of PH within the time slot you can ride back for free.
• There's a stand near Breakout Waikiki that is a hard sell timeshare sales pitch (couples only). If you're willing to sit through it, they give you $150 towards an excursion or a free meal and a $120 Visa gift card (as of March 2019). If you want the exact location, message me.
• You may think being a Costco member will help you out on expenses and you're probably right but know that the busiest Costco in the world is on Oahu and they claim 1 in 4 people have membership so plan accordingly (think shopping for the latest toy on Christmas Eve)

Pride Of America

I have to be honest, this was hands down the most expensive cruise I have taken and it was the worst cruise ship. I had a great time but there was a lot left to be desired.

• Entertainment was very underwhelming - I believe unlike other mass-market cruise lines, NCL's entertainers are on multi-month contracts just like other staff. This tends to be bad for entertainers like comedians (how many different sets can they have prepared) but should be better for magicians (you shouldn't have to rely on the suitcase you get through security at the airport). I have seen a Vegas quality magic show on NCL before (Norwegian Spirit last November) but this act was honestly no better than a birthday party. I could go on but I will summarize it as this: On Carnival, I struggle deciding what I am going to do because of so many good things where as on this ship, I struggled to find anything I actually wanted to do.
• Beer prices were outrageous and included a mandatory 20% gratuity and since you spend a LOT of time in port, taxes too. In each port, I found a better selection of beer right off the ship for at least 20 - 30% cheaper than on the ship. If you do drink on the ship however, I highly recommend the Gold Rush Saloon as it has a couple of beers on tap you can't get anywhere else. It has a self-serve popcorn machine and is adjacent to the buffet so you can get self-serve ice cream too.
• The food was mediocre (main dining quality was about the same as the buffet which was good but not great). I didn't spend the money to try any of the specialty dining.

Update: One thing that really stood out as being a good thing is that the room had 3 US standard outlets!!!
Why Does It Cost So Much

• There is no casino to subsidize the fare cost
• It is a US Flag cruise ship which means it has to abide by US labor laws (this is an indirect result of the Jones Act as it doesn't travel to any foreign ports)
• Hawaii not only has a sales tax but a tourist imposed General Excise Tax which of course NCL passes on to you
• Exclusivity - unless you want an extremely sea day intense cruise from California, around Hawaii, to Mexico and then back to California (or similar) cruise - they're the only show in town

Hint: You should get the NCL Mobile App. It includes dinner reservations, account charges, dinner reservations, deck plans, passenger to passenger chat for an additional fee ($10 vs Carnival's $5) and other nifty features.
Observations
I was astounded by the number of first time cruisers I saw (based on their ship card color). Because so many of the employees were American, I was also surprised by how many told me that they were on their first contract and wouldn't be back. The people (both employees and passengers) were incredibly friendly and most everyone seemed to be having a good time. I didn't see long lines at guest services. I mentioned earlier how this was the worst ship I had been on - and, while true, shouldn't give you the impression that I didn't have a great time. For my traveling companions, they had nothing to compare it to and other than the entertainment - they had no complaints at all and loved it.

Day 1 & 2 Maui (overnight)

If you have ever been on a Caribbean cruise and you didn't feel like paying for an expensive excursion you could always just walk off the ship and go to a beach or a shopping district or a friendly bar - something. This is not the case in Maui. Where the Pride Of America docks there is absolutely nothing (it took 10 minutes to walk out of the port with chained link fence on both sides only to end up about another 10 minutes away from a strip mall). I do want to point out that the strip mall did have a few artisans selling things out on the sidewalk but this was far from what you will be used to at other locations.
So what to do instead?

• Rent a car if you want to go on your own - day rentals are common and you will be in port overnight. You will have to do your own research as to what to do as I booked excursions for both days
• Go up to Haleakala Crater for sunset or sunrise. I went for sunset as sunrise required leaving the ship at 3 AM. I can't stress how amazing this sunset was at nearly 2 miles above sea level. If you go, take plenty of warm (think Maine winter) cold. It was 44 degrees without the windchill when we arrived at around 5 PM (still sunny) and the temperature dropped significantly by the end of the sunset (around 6:40 for us but varies based on time of year).
• Road To Hana - I didn't take this excursion but it is extremely popular. Most guests I spoke with said they absolutely loved it though a few called it the road to hell (it's an all day excursion)
• Maui Northshore & Waterfall Walk - This is the one I took because it was rated as "easy" and one of my traveling companions has mobility issues. There is an alternative called Waterfall Hike that you may want to consider. This was a great excursion which took you into a historical town for lunch (delicious) and gave you some free time to explore the artisans (glass blowing, jewelry making, etc.) before taking you to the private access Wailele Farm. The waterfalls you can walk to (as opposed to hike to) were not breathtaking but overall the plants and flowers here were amazing. You will get an opportunity to eat many of the things you encounter so if you're feeling adventures, give it a try.
• Choose another of NCL's Excursions
• Choose something from Viator

Day 3 Hilo Hawaii

This is the first of two days on the island of Hawaii and it is on the eastern (very wet) side of the island. Normally doing two excursions in one day is a not recommended. I would make an exception here because the Botanical Gardens are not to be missed. It is a short excursion (2.5 hours), is relatively inexpensive (you can even do it on your own) and is offered at multiple times allowing you to get another excursion in.
Recommendations

• The Botanical Gardens - either through NCL or directly with Hawaii Tropical Botanical Garden - they have social media as well if you have questions. Tip: One of my traveling companions said walk through twice - once looking down and once looking up because there is just so much to see.
• Go zip-lining. I happened to choose Zipline Through Paradise as it had a tandem/parallel course (you got to zip at the same time as someone else). You can even hold hands on one line for a very special photo. You may even want to book directly with Kapohokine
• Choose one of NCL's excusions
• Choose one of Viator's options

Day 4 Kona Hawaii

The other side of the island is a stark contrast to Hilo as it is dry/desert climate. It is the only tender port on the cruise. Unfortunately, we didn't fare very well here on excursions but shopping and beer was good.
It has been on my bucket list to be in a real submarine and go over 100 feet to below the surface to the ocean floor. That's what 3 of us did here in Kona and while I am glad that I can now say I have done it (105'), the experience itself was underwhelming. To not interfere with the wildlife, the sub doesn't use any artificial lights nor does anything to attract the fish to your windows. This means almost everything is a monochrome blue (the color red doesn't exist at this depth for instance). It's also nearly impossible to get nice photos out the windows even though they are clear enough - just not the right conditions. Now, I met a guest back on the ship that said he had a phenomenal time on a sub that wasn't sponsored through NCL but I'm not sure what it was.
The other guest in my party decided to go on the Gold Coast & Cloud Forest excursion and was also not impressed. The gold supposedly comes from the Hawaii state fish (yellow trigger fish also known as humuhumunukunukuāpuaʻa) but apparently they haven't been plentiful enough to turn the coast gold for years. She also said if she was a coffee drinker, she probably would have enjoyed it more (they are famous for their coffee).
Recommendations

• If you would like to buy coffee at a discount, a tour guide let me in on a little secret. To be called Kona Coffee it has to indicate what percentage is from Kona (i.e. 100%). Well, geography being what it is, the line between Kona and the region to south is arbitrary (created by humans) so buying coffee labeled just across the boarder (I forget the name of the place - I don't drink coffee) is 25% cheaper
• If you want to see the pretty coral and reefs, consider a glass bottom boat ride. The bartender I chatted with told me that she used to work on the sub and a much more beautiful experience was the glass bottom boats.
• Normally, the closer to port you are the more expensive things are - like souvenirs. That may in fact be the case in Kona but I found the prices at Whalers General Store to be very competitively priced. Many of the same items I saw at stops before here were at least 20% cheaper.
• Have a drink or 6 at Paradise Brewing Company. I was fed up with the prices on the ship so I checked this place out (there was another one further up the street with a fairly large beer menu as well but they weren't very friendly so I moved on. I sat in here for hours (was one of the last tender boats back to the ship). It was extremely friendly - the beer was good, the food was good - I would definitely recommend.
• Take an NCL excursion
• Take a Viator option

Day 5 & 6 Kauai (Overnight)

Remember how I said you have this ideal image in your head of what Hawaii is and Oahu doesn't meet it. Kauai exceeds it - I fell in love and if I ever go back, I will just fly directly here and stay on this island - it is that good.
I am not going to suggest you do anything other than exactly what I did because I couldn't possibly imagine having a better time.
Recommendations

• Day 1 - Best Of Kauai. I have no idea if a similar excursion can be booked elsewhere because it included 5 stops (Waimea canyon, Spouting Horn Park, Keoki's Paradise for lunch, Opaekaa Falls and Wailua River Fern Grotto). If you want to "build your own", just go to Waimea canyon and dine at Keoki's Paradise as they were the highlights of the day. If you are into photography and have gotten tired of lugging all of your lenses around, today is the day to have it all at the ready.
• Day 2 - Mokihana Helicopter - There are no words to describe how amazing this was. I did discover that can get it substantially cheaper directly with Blue Hawaiian Helicopter Tours.

Now, there's more to the story than just these two excursions. First, since you're overnight you can stay out as late as you want. I asked our tour guide where an affordable place to get good beer close to the ship was. She recommended The Nawiliwili Tavern (or just the Tavern). It happens to be a 2 minute walk from one of the free shuttle stops and they have great pizza, beer and pool. Secret I learned this is also where a lot of the crew from the ship hang out after they get off at 9PM so if you want to have a real conversation and ask real questions - this is the place to do it. Once the bartender realized I was into craft beer and trying all they had, she told me about a brew pub not too far up the road that I really wanted to try but ran out of time.

Napali Coast (still day 6)

The cruise ship leaves port early (circa 2PM) and instead of heading to Honolulu backtracks around Kauai. There is a portion of the island that's only reachable by air (helicopter) or by sea (cruise ship) and I was fortunate enough to do both. Actually, our pilot said that a few of the beaches can be reached by a hiking 11+ miles but it isn't an easy hike. In any event, this is where the opening scenes of Jurassic Park were filmed if I remember correctly - utterly gorgeous. My pilot also let me in on a little secret - that the captain times the cruise ship to sunset when the coast is all lit up in spectacular colors so be out on deck with camera ready.

Day 7 - Honolulu (Pearl Harbor & City Tour)

I made a big mistake here. I booked a late flight so I could go to Pearl Harbor and then get dropped off at the airport. We had already done the Circle Island Tour and none of the other offerings were of interest. This was a mistake for two reasons.
Reason 1: Exhaustion
After having spent 5ish days in Waikiki and then taking a 7 day cruise, we were wiped out and really didn't have the stamina to really take it all in.
Recommendations

• Eat a big breakfast as this tour didn't include food
• Bring food for the tour and possibly the airport (see airport notes below)
• The cheapest place to get hot dogs at the time was at the Missouri ($6 as of March 2019)
• If you are using your phone as a camera, practice taking photos against the bus window as the city tour took you to some neat places but they didn't stop to let you off
• The tour includes the Missouri and the Arizona - everything else is additional
• At the time of this writing, the Arizona was still under repair so you only took a boat close. You will be watching a very emotionally moving video before the boat ride so sit as close to the exit doors (front left) as you can so that when it's over you can pick one of the corners of the boat to get unobstructed photos from - they don't allow you to stand up and they don't play. Oh, and if you are sensitive to loud noises - when the bomb actually drops on the Arizona it is about 10 times louder than the rest of the film so be prepared
• Our guide got tickets for the Arizona at 2:15 PM, helped us navigate the shuttle over to the Missouri and told us he would see us at the bus 3:30 PM. If you're not comfortable navigating on your own then this is probably not the tour for you
• It's only 5 minutes from the airport so if you want to stay longer because of a late flight it would be fast/cheap to go on your own - just ask to get your luggage off the bus

Reason 2: Airport
If you have a late flight home, I'm sorry. All of your checked bags have to be screened by agriculture (certain plants are not allowed to leave the state) which is airline specific and unless that airline is running flights all day (looking at you Alaska), then you will have to wait for them to open before you can even check in. While you wait, there is essentially no place to eat (Starbucks and a bar that serves hot dogs for $12.50 - yes, $12.50). I recommend you keep some food with you for this reason. They do offer a baggage hold service but the prices were ridiculous (4 checked bags for 24 hours was $100). Sorry if it seems like I am whining - it was the end of a long trip and I was returning to reality.

Update: Viator

In this post, I have provided a number of links to NCL's excursions, directly to the vendor and also to Viator. Viator is part of Tripadvisor and generally speaking, you can trust the reviews. On most of the bookings, you can cancel for a full refund up to 24 hours in advance. They are competitively priced and you can usually get a discount. For instance, new customers will get offered a 10% discount off their first purchase. Companies like Ebates and TopCashBack will offer an additional 3 to 6% cash back as well. Use a credit card that gives back 2-4% on travel and it can really reduce the price. I haven't had too much trouble figuring out what vendor was being used through Viator so you could just book with them direct too and just use them as a way to find fun things to do and use the reviews to distinguish between what's good and what's not.