42 - 16 freewheel, 42 - 15 fixed. I've climbed really steep short stuff (>20% for one block) and some long climbs (Monte Sano Mt. up Bankhead) which is three miles long from the Five Points neighborhood. 5.8% grade. I always flip the wheel to the freewheel side for the descent.

On the flats, I can spin out the 42-16 pretty easily but it's nice to have when I'm commuting and carrying a bunch of stuff. Bike originally had 42-17 fixed but that was too low. I was racing against a couple of dudes in an alleycat and they just moved on past me like I was sitting still.

Whatever works for you; go for it. I've seen some bikes with insanely high gearing and knew it was all for show; the rider was not that good. A good rider had his bike running a 52 - 15 for one race. It was funny to see him get started, he did a running start. Once he got it cranked up he was gone. Until it came time to slow down or stop. Had to work hard to control that beast. Then it was another block of getting up to speed. He changed to a more manageable gear after that.