Buzz, Nation's Friday night party, lasts until 6am and attracts top DJs from across the globe. Among others, I've recently seen Sasha, Danny Howells, Satoshi Tomie, and bi-monthly residents Deep Dish.
Dress Code: don't wear anything you don't want to spill on
Other clubs ( not necessarily my favorites, but they are fun):
Chaos, 17th & Q NW - gay, latin on Thursdays, Theme fridays, disco Saturdays.
Badlands, 21st & P- gay, house music.
Club Element, 615 6th street, Beautiful club, just getting started. International on Firdays and saturdays (so far).
Diversite, 14th & P. There are many more.
I guess, the best thing is to check these links:
citipaper.com (look for dc)
and pick what you like. Have Fun!
Almost all bars/clubs in DC close around 2 AM. Exept for Velvet Nation, in SE. Nice large club (not my scence because i do not like their music) but a lot of people like it.