24 miles is fine on a fixie, but I +millionth on the gear down. I have a very flat commute, 18 miles one way, and I'm riding my single speed 42x17. If it was fixed I might go 44x17 or 42x15, just so I wouldn't spin out, but I like where my RPMs are for most of my ride-right around 90.
Your knees will get sore on a flat commute with tall gearing unless you have the uber-strength to spin that tall gear!
Fixes are fun, and if you feel good with the geometry then go for it.
Personally I wouldn't ride a track bike outside of a track, but I have short arms and like a more relaxed position for my commute.
Good luck!