Congrats! Although I would pick schools based on how many faculty are there that you'd be interested in working with and whether the location is minimally livable, I would say one thing about Caltech. I live in the city of Los Angeles and I wouldn't consider Pasadena really a part of LA. I wouldn't let the proximity of Pasadena to L.A. be a selling point for you. If you don't have a car, forget it completely. If you do, the traffic will be enough of a hassle to keep you from going very often. Potentially you could live in L.A. and commute, but it'll be a pain.
Just thought I'd give some advice in case you were partially drawn to Caltech because it's "in LA". Hope it helps.
Also, I would have to respectfully disagree with Spew - every Caltech student I've met (grad and undergrad) has been really unhappy with their work-life balance and couldn't wait to get out. Caltech is a place for type A personalities to thrive, but can be a bit much for everyone else.