hey raven, it seems like everyone is answering based on location. location is important, but i think you really need to look at the qualities of the school and where you'd be happiest (also, it's ok if you'd actually prefer st. louis to palo alto, you know. i sure would).
I've heard a few times that Stanford students oftentimes don't make the best residents (once from a residency program director--don't ask me why she brought this up...), but who knows. Could just be some jealousy rumor or something.
If you want to wow people who don't know anything about medicine, go to stanford. Wash U may be more respected within some medical circles, but in the outside world, it's name doesn't hold the same weight as Stanford's name.
That way, if you decide during medical school that you want to go to business school or run for public office instead, you'll be in good shape. Stanford's name might also help you if you're an fp in private practice or something.