I cruise a lot and I've learned to pack only a few colors - (I do black, white and khaki and throw in a piece or two in red or yellow) This way you can mix and match and get a lot more mileage out of your wardrobe. Why 2 weeks of clothes? I thought you said 5 nights? Don't forget, you can wash out a few things and wear again. Believe me, no one remembers or cares if you wear things twice!
And don't forget sunscreen and hats. The sun can be brutal.