I commute 3-4 days/week on my road bikes. Generally I ride a steel lugged De Bernardi that I've set up for commuting with a Carradice Barley seatbag and rack, with several blinkie lights and a headlight. The seatbag is large enough to carry several articles of clothing as well as cell phone, lunch, eyeglasses and other gear. Occasionally I ride one of my Merckx road bikes when I feel like going faster. The main problem with the Merckxi is limited space in their seatbags, so I just ride them when I don't have to bring any extra clothes or lunch.

The roads are in good shape on my commute route, so I have no problem commuting on tires ranging from 700x23 to 25, but my main commuter has Panaracer 28s -- mainly for flat resistance. I try not to ride in the rain, so fenders aren't an issue -- and my experience is they really don't make much difference when it's really raining out anyway.

If I was looking for a new commuter bike, however, I would probably buy a frame like a Soma Smoothie or Salsa Casseroll that has eyelets for racks and fenders.