Re: Warning: Pet Peeve ahead.
Where is the Flash's top speed listed? 'Cause I don't remember anywhere saying he can move at .9999999c.
At a velocity of .9999999c, assuming my calculations are correct, he would be experiencing 2236.068 times as much time as the rest of the world due to relatavistic time dilation. That means that if he maintained that speed for one day, he would age six years. Which means that even if his lifespan was, say, 100 years, that entire lifetime would be eaten up in sixteen days of uber-superspeed. So, yes, Flash could potentially pwn all given those sorts of maximum speeds, but using that for sufficiently long time periods would kill him. I imagine that sort of speed would be reserved for absolute emergencies, even if he can reach that sort of top speed. [/physics major relativity rant, ignore if it annoys you]
That being said, superspeed is an awesome superpower for crimefighting. Probably hella obnoxious for its holders, though, since slowing to normal human speeds would be an inexact process, and they would always be moving just a little faster than the rest of the population. Not enough to prevent a fairly normal life, but enough to make it feel like everyone else was moving in slo-mo, and potentially make people think you're severely ADHD and/or dangerously over-caffeinated.