feel free to pm me for more info. i had the exact same choice as you to make, got the wash u acceptance in dec and the sinai acceptance a week later. i dragged my heels till may 13th because i was so desperately in love with new york city.
as far as schools go though, to be honest there's really no question as to the "better" school - ranking, reputation, facilities. of course, both schools are excellent and sinai had a really laid back and cool student body as well as awesome location. people are gonna talk about sinai's hospital financial crisis etc, which may or may not have an effect, and is certainly not something wash u seems to have a problem with. what did it for me finally though, were the first year students at wash u. i visited twice and really had a blast with them. yeah, they work hard, but they're also laid back and fun to be with. st. louis is no new york, and like someone once told me, "it doesn't try to be either" and there are benefits to living somewhere more quiet too. it all depends on what matters most to you.
my plan is to get out of st louis for residency, hopefully to either nyc or cali, and i think that wash u will certainly help me in hopefully attaining this goal. so for me, at this point in my life, the draw of nyc wasn't quite enough to pull me away from a school as great as wash u is. there's always taking a visiting rotation there come 4th year...
lab-rat, you're on the sinai waitlist right? good luck and hope it works out for you...
oh, and wash u actually tied with hopkins for #2 this year...however much meaning you can choose to assign to or not assign to rankings, while rankings sure don't mean everything, it certainly doesn't hurt... 🙂
siempre, looking forward to meeting you!