If you work downtown, you may initially think that all the parking compaies (Central, American, APA etc) are the same.
BIG mistake. I've parked in both Central & American lots... American is head and shoulders above Central for maintaining their lots.
American's lots are cleared of debris (such as beer bottles) every week, and periodically hosed off if a flock of pigeons has landed nearby. The same can't be said for their competitors.
Since the price to park is about the same, I'd recomend an American lot, unless you want to be stepping over pigeon poo and beer bottles on your way to work.