Velvet Nation, Washington D.C.
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.