After getting rear-ended on my road based commuter, I decided I needed a bike that would give me escape routes. I wanted to be able to go over the curb or off on the shoulder or even into the ditch and come out unscathed. So i bought a Giant Talon, fitted it with some 37c street tires, full coverage fenders, lights and a rack. It works great. Definitely slower than my road bike if there's wind, but not much slower if there's not. I'm not much for hitting the trails, but it's nice to know that in 15-30 minutes I can be trail ready if I wanted.

Hope that helps.