New York is one of the most culturally rich cities in the world. The number of cultures and ethnicities represented combined with their strength in numbers make NYC the diverse, vibrant city that it is. Due to the cultural explosion that is NYC, one can see all kinds of great music, art, and especially dance. If you're tired of going out to bars and looking for a cheaper, more interesting way to fill your weekends, taking dance classes is a great way to go.
Take advantage of what NYC has to offer. Few cities in the country have as many places to take classes and different styles available to learn as New York. Most of the classes are very inexpensive too. Salsa, meringue, tango, jazz, ballet, modern, tap, hip-hop, African, etc. etc. There are places all over the city to learn them all, and most classes start around 15 dollars a session. Compare that to what you would spend in a night out drinking.
Whether you want to just learn a few new steps or master the form, dance classes are a great way to spice things up in your life. They're a great way to meet people. Got a crush on a special someone? Dance classes are a great way to get to know them more intimately. It will score you a ton of points being willing to put yourself out there, and you'll have something really fun to bond over.
The sky's the limit with dance classes in NYC. Even if you're rhythmically challenged, they're classes. The idea is for you to learn and improve. As long as you've got a willing attitude and don't take yourself to seriously, you'll have a ball. Having some moves to show off next time you're at a club never hurts either.