Done carefully, you'd be surprised how few wrinkles your suit jacket will get, especially if the suit is one made from a contemporary fabric that resists wrinkles--I have a Jos. A. Banks Traveler Collection suit that I use especially for trips that resists (but doesn't completely avoid) wrinkling. A steamer or hanging in the bathroom during a shower will really help. I tend to fold the pants separate from the suit and put them in the carryon but outside the garment bag.