Another recommendation for the Continental GP 4 Seasons, but I recommended going up to 28mm size if you have the clearance. If you have to commute on city streets or really any roads that are not in good shape, the 28mm will add some comfort without adding in any significant way to rolling resistance. I weigh 160 lbs., wear a pack that adds another 5-7 lbs. and the bike itself is around 21 lbs., and I inflate the rear to 80 psi and the front to 75 psi. I don't get pinch flats at that pressure but I do get a pretty comfortable ride.

I purchased mine this summer after flatting a couple of times using another brand, they have roughly 1200 miles on them, I have yet to flat and they are showing minimal wear. I ride on some pretty beat up urban roads around the Boston area and the tires have so far proven to be very durable. I've found them very easy to mount, something well worth considering as a commuter.

As for price, if you go into your LBS, expect to spend $125-$150 for a pair, but they can be found on Amazon for example for around $90-$95 per pair.