Hanging in the La Guardia airport after a long weekend taking trains up and down Manhattan. The infrastructure and planning involved in the subway system is mind-boggling, with 3 and 4 different lines running at different levels in the same place. It shows that great public works aren't things that can't be done (unlike what many 262 types say), but it's a matter of priorities and will.
It's also a lot harder to be fat in NYC, because walking and stairs are such a part of everyday life. Also being in contact with other cultures is unavoidable, but you can also insulate yourself into your own social class quite easily, depending on where you shop, eat, and live.
Glad to be heading home, but it's been a great getaway (other than the 8.75% sales tax-that's quite a kicker).