1. Boston. (obviously)
2. New Orleans. I love your delicious food, your fun bars, your friendly people with those strange accents, your voodoo shops, and the way you make me feel like I'm in another country. Get well soon.
3. San Francisco. Beautiful scenery with a funky vibe.
4. Miami. What can I say? I love the nightlife. Electric boogie.
5. San Diego. Sunshine, beaches, and Mexican food, without all the smog. Stay classy.
6. Chicago. A big, fun, city where there's always something to do. The best of the Midwest.
7. Philadelphia. Cheesesteaks. Allen Iverson. Bizarre new year's day parades.
As a corollary, and I do expect to catch some flak for this (especially from all those Seattle-lovers):
List #4...least favorite American cities
1. Seattle. Crappy weather and expensive coffee? Thanks, but no thanks.
2. Washington, D.C. I know it's the nation's capital and all, but this city has no soul.