LivingSocial: If it's late enough on a weekend night, go to The Guards and head downstairs to the now-defunct (in name) "Gryphon Room" for a hot dance floor and cold beers.
LivingSocial: Try the "After Dark" menu, good between midnight and 2 am on Fridays and Saturdays. The bison burger is delicious, and the perfect finish to a night out on 18th street.