I most often run 42x16 on my fixed gear. However, I change up quite a bit depending upon what I'm going to be riding. I just did a hilly 200k brevet with a 45x17 and I was a bit over geared. For general road riding, I think a 70 inch main gear with a 60-65 inch bailout hill gear on the flip side is a pretty good setup for me.

Dave