Thanks for all the suggestions/pictures Lots to think about.

I'm a PhD student, so I need to have the ability to carry a bag with me off the bike. Even if I could just toss my normal bag in one of the panniers and make sure it was waterproof, that would be fine. I just have to be able to take my work bag with me.

ETA: Thanks for putting the CM's on that bike. It looked small. I've had a 48, a 50, and a 47 (current bike), so my bikes will never be much bigger than that. Good to know what it looks like!