Lots of good suggestions here. Keep 'em coming. I have a 25 mile roundtrip so I'd like to be able to bring about a week's worth of clothes. I sometimes ride my mountain bike (usually only if I'm riding with a coworker who's on a mountain bike). Mostly, I'm on a road bike so I can get on the road bike and get some real miles in most mornings.

I think I'll be putting a rack on the mountain bike and hall clothes once a week. Sounds like rolling in regular panniers is the way to go. Any recs on a good set of panniers and/or rack?