I think capes look cool in comics, but in real life they would get in the way it seems. In comics I just think there's something cool about a cape flowing in the wind.
I do think that if you're going to wear a cape you have to be able to fly though with Batman and Spawn being the exceptions.
Cool costumes:
Guy Gardner
Eradicator (not the sunglasses version)
Mr. Terrific (Michael Holt)