Good Question!
A few things to keep in mind,
1) You will have at least 1 formal night. Read the documentation on this, but the first night has become a relaxed wear night as it's just to much of a hurry for everyone to get dressed in the short window of time between luggage delivery and first seating.
2) There are guest laundries on board. Bring quarters. There are also irons/boards free for use. Also be prepared to run all drying twice, as once will only bring them to damp, not dry.
3) You usually need to pack a bit more because of the number of outfits needed. as an example, for me a guy, except for the formal night, I went with polo's and dockers for the nights, but tees/shorts for during the day as it can get very muggy.
I'd suggest you make a list of the days and come up with a rough plan for the clothing.