Just thought I would share what to pack for cruises and some guidelines. You can try to "mix and match" outfits, so it is not necessary to pack different outfits for each day and night of the cruise.
Example, for my 5 night cruise in September, I may only bring 2 pairs of shorts and 2 t-shirts for wear during the day, and just mix and match, and 2 pairs of khakis, 2 button down shirts for evening wear on the non formal nights, slacks, a nice button down, and a sport coat for the formal night.
Depending upon where you go, you may or may not need bathing suits, sunblock, sunglasses, and/or a hat. Also, you definitely want to bring a camera (photo or video), although it's a bit of a hassle for video cameras through airport security, as they have to come out of their cases.
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)