There are the garment bag panniers and they are very nice. I do business casual at my office and manage to get my clothes to work in a single pannier (with lunch and stuff in the other one). I fold up my shirt, then lay it, my underwear & socks, and my towel on the pants and roll them all up. It comes out at the other end reasonably wrinkle free (I don't think it would be any better in a garment bag pannier). I can use a locker room at work, so when I get there I simply take all that stuff out and I have my towel and underwear handy with the shirt, pants and socks ready to go.