79pmooney and I are among the very few (I would guess) people posting on BikeForums who have been riding fixed gear for decades. In my case, I got my first track bike (a Helyett Jacques Anquetil model with Reynolds 531 frame and pretty junky French components) in September 1964, so almost 56 years ago. I used a 51/19 gear combination, which is 70.5 gear inches.
Now, at 68, I mostly ride a Specialized Langster (the aluminum model from the first year of production) or a Felt (aluminum) TK2. Both have 48/18 gearing, which is 70.1 gear inches. I think I'm about ready to go to a 19 tooth fixed sprocket, though.