Try packing your clothes in 2-gallon zip lock bags. I place one item in each bag, sit on it to squeeze out the air, and then layer them in the suitcase. When we get on-board, we hang everything and never have to worry about wrinkles. If something does need a little touch up, just hang it in the bathroom while you shower and the humidity will have it looking like new.
Side benefit - we changed planes in Atlanta this past Spring during a thunderstorm. Our bags were soaked from sitting on a luggage cart outside, but our clothes were still dry when we got to the ship!