I also am a city commuter, to school and work. I highly recommend the Carradice panniers. I have the bike bureau which I bought from them over a year ago and I have never regretted the choice. The quick-release is excellent and totally reliable, and the bag is good-looking (I think). Here's a link to them:
http://www.carradice.co.uk/index.html
They are in England, but I actually paid less buying from them - including shipping! - than I would have at any of the dealers here. Do research, though, the dollar has lost value since then.