Alright here is where I am going to get BOOed by all of the RC lovers. This is where Carnival has RC beat. They have self-serve laundry facilities on most floors, and in those rooms they have FREE irons. It is a great thing to have.
Usually when I get out my dinner clothes for the first dinner I got ahead and iron my pants and the shirts that are really wrinkled. Then toward the end of the cruise we usually do one or two loads of laundry while napping or enjoying the sun. That way when we get home everything is not dirty.