We are in California, so Hawaii is our backyard playground! We go often, and love each island. If you are able to, do rent a car; it is the best way to see the islands. If you are taking children or teens, a condo is your best choice of lodging, for you can save a lot of money by preparing some of your meals, and there is usually a swimming pool on the premises. Food is quite expensive in the islands. I love the farmers' markets and swap meets, where there are always new foods to taste and enjoy. Ethnic restaurants are plentiful, and the fresh seafood is fabulous.
We have used Pleasant Holidays packages several times, with car, hotel or condo, and plane fare, and have been quite happy with them. They have been flexible, allowing us to, for instance, stay in a hotel on one side of the Big Island, but at the same time letting us to make our own reservations at our favorite bed and breakfast on the Hilo side. We also were part owners of a condo on the beautiful green island of Kauai for a time, and have stayed at many hotels and condos on the various islands.
Read Trip Advisor, talk to friends and family, and watch for good deals...There are many out there. Get some guide books from the library, read through them, and think about what is important to you. Air conditioning might be quite high on your lists of "must haves" because it is hot in this tropical climate.
Do you want to snorkel? Do you want to learn about Hawaii's history? Do you want to lie on the beach and do nothing? Do you want to sightsee? How about visiting botanical gardens or seeing whales? Some islands are better than others for different activities, and some times of the year are better for certain activites such as whale watching. If it's important to you to see an active volcano, you have to go to the Big Island. If you would rather see a dormant one, go to Maui. On Oahu, Pearl Harbor , the Bishop Museum, and the Polynesian Cultural Center are must-see attractions. But if you stay only in Honolulu, you have missed an opportunity to experience the laid back lifestyle that is so delightful in Hawaii. Better to divide your trip between Honolulu and a less congested area.
I know people who have liked the "Hawaii Sampler" of the NCL cruise, but we took it with three other couples and were not impressed. The dawns and dusks of this tropical climate are full of wonder, and we missed being on the islands for those. The birds and the trees and flowers kept calling us ashore. We found it frustrating to have to return to the ship after each shore excursion's hours were up. If you are into the "cruise" part, the buffets, nightclubs, swimming pools, etc., I expect it is fine, but if experiencing Hawaii is your main goal, my personal opinion is: make another choice.
Don't spread yourself too thin and try to visit every island in one trip. Choose one or two and really explore them, and then next time you can choose a different one. And which island is our favorite? It's always the one we visited the last time we were there!