We tend to dress up on our cruises and we pack all of our evening wear on hangers covered with plastic dry cleaning bags and put them in suit bags along with our dress shoes (wrapped in tissue paper). I usually pack them last thing the night before we leave and then leave the suitbag out open on the floor ready to be zipped the day of the cruise. Most of our cabins allow us to have laundry/washing/ironing/shoe shine free but if you are staying in a cabin which does not, it is a nominal charge to have your clothes ironed. You may want to hang them on a hanger in back of the bathroom door (which is closed) while you take a shower--it gets good and steamy in the bathroom and may de-wrinkle them a little as well. For other things which I do not want to wrinkle, I may wrap them in tissue paper with paper in the sleeves and in between folds.
Good luck and enjoy your cruise, wrinkled clothes or not!