Hi, Carolyn ...
Follow Donna's advice about the dry cleaner's bags and you shouldn't have a wrinkle. I once had a LINEN outfit packed that way that travelled halfway around the world, stayed in a suitcase for three days before unpacking and NO WRINKLES.
Expect to pay about $3 to have a dress pressed, if you need it.
pamda -- CM First-Time Cruisers Editor