You should check with your cruiseline to see if they offer ironing service. We had it on HAL for only $15/cabin, and they ironed anything we gave them for the entire week! It was the best 15 bucks I've ever spent on a cruise. Plan for a 24-hour turnaround; your evening wear will be hanging in the cabin when you come in to get ready for dinner.
Cheers,
MaryC