Any tips for a 20 year-old moving to Washington?

I'm 20 years old, moving to Washington to intern with a government agency. I'm really excited about the chance to live on my own in a new city. Being a pretty intellectual guy, I obviously want to visit the museums, monuments, etc. I've never even been to DC as a tourist so this would be fun. However, I also want to experience the nightlife. Are there clubs that I could go to, or bars that let you in but don't let you order alcohol? Are there any other ways I could meet girls my age? I'm thinking of living on a college campus, like GWU. Any advice would greatly be appreciated!