It has already been mentioned and I am just repeating... for commuting a bike that will accept wider tires (and fenders) makes sense. You can run lower pressures (about 50 to 60 psi) on 700 x 34/35c tires and not worry too much when you are unable to dodge cracks/potholes/rail tracks on the road of which there are plenty in a typical commute. Wider tires also mean that you can ride over drainage grates without fear of your tire getting caught and thus causing damage to your rims.

Having said that, wider tires in general are heavier and less aerodynamic than thinner tires (23/25 mm). I would not want to be on wider tires (and a heavy bike) in a race/fast group ride where I might have to accelerate hard to bridge a 50 meter gap where strong head or crosswinds are blowing.

I think I found the optimal commuter tire (Spring to Fall) for my CX bike... it is the Continental Cyclocross Speed folding tire. It is lighter than tires with wire beads but at the same time robust enough to withstand the challenges of daily commuting over a variety of surface roads.