I didn't paint the floor as mine is a working garage and not just for storage. Every garage I've seen that has painted floors and is a real working garage (jackstands, floor jacks, dragging heavy parts, welding, etc) just didn't seem to stand up.
I think that U-coat it is probably the toughest, and my only option as race-deck and carpet wouldn't look good or wouldn't make me comfortable re fire hazard leaving the garage after welding spatter had blown around. So, I sealed the concrete (steel and fiber reinforced so it is a little 'furry'), and don't worry at all about tire 'pick up' or scratching it with the tractor loader or backhoe....which I park as far away from the Cayman as possible!
I'd love to build an uninsulated twin garage to just dry store stuff, but the wifey has other plans for my time.