New York City
The Big Apple. Centered on the towering blocks of Manhattan and extending far north to the Bronx and out east to Brooklyn and Queens, NYC is one of the most well known cities in the world and is jam packed with things to see, do and eat.
To be honest, I'd never had much interest in visiting NYC, but I was pleasantly surprised. Having seen so many massive third world cities, I'd never really seen a massive first world city (except for London) so this was really something else. It seems that every stop on the (huge, cheap and 24 hour) subway system dropped me in a completely different city, with a different culture, different food and different feel. Each area was distinct, but always interesting. We spent huge amounts of time just doing that, tubing around, getting out, walking and eating, with very little in the way of plans, and it was great!