The first time I ever saw Hawaii was a cruise around the Hawaiian Islands with Norwegian in 2003. Since then we have returned for the cruise in 2010 and just last week. We especially like all the island time and minimal time out at sea. The ship "Pride of America" is awesome and we typically eat every night at one of the specialty dining restaurants. For this particular cruise I would highly recommend a balcony if you can swing it. We had breakfast delivered to our cabin almost every morning and ate out on the balcony.
While in Kauai I highly recommend you go to Kipu Ranch for the ATV tour which stops at several locations where many films were shot. Also, highly recommend the Zodiac Snorkel Tour in Kona.
Have fun!