I'm "only" 50 but I just got my first fixed gear bike this year. 46x18 for 68 gear inches. I configured it fixed. I figured that if I didn't like it it would be easy enough to put a freewheel on it.

I like it.

I got it because i thought it would be fun, that it would help me improve my cadence and build leg strength. Nailed it on all three counts. I also found that it has encouraged me to coast less when I am riding my freewheel bikes. The bike I purchased has a more of a "road" than "track" geometry but it has a real short wheelbase and is easy to flick around, accelerates well and is just all around a blast to ride.