I spent one night in New York City, on my way back from another vacation. I wish I had more to spend there, but enjoyed what little of it I had. Times Square was quite a spectacle, even in comparison to what I've seen in San Francisco. My group had an early flight out the next morning, so we went shopping at the original Macy*s, then cabbed it back to the airport.
My favorite vacation was spent camping in Black Rock City, Nevada, site of Burning Man. Each year for one week, a community (now over 50,000 strong) erects a city in the middle of the Black Rock Desert, dubbed Black Rock City. At the end of the week, a huge statue of "The Man" is burned, in a ceremony that carries many different meanings.
I've taken a couple vacations to attend Coachella, an art/alternative music festival in Indio, California. Best show I've seen down there would be a tie between Daft Punk or The Chemical Brothers.