My patrol bike is a pretty standard mountain bike with road (Continental) 1.95 X 26 tires. I inflate them to the max listed, 60 pounds, and get a pretty comfortable ride.
The bike is set up with a mild riser bar with slight pullback, for an upright position. (we need to be able to see...) Quite comfortable for tooling around the campus, and capable of a fair turn of speed. I would think such a bike would be a fine commuter for shorter trips.
For anything past 5 miles or so, I'd rather ride one of my roadsters.