DC: Need a place to continue the party after a formal event

I have a formal event to attend in downtown DC on a Saturday evening. I'm taking a date and afterward we're going to want to go somewhere fun, perhaps bringing out others. Problem is that the places I usually haunt would be fine, but not exactly keeping with the well dressed theme. Can anyone think of a place for a youngish couple or crew to continue having fun in the city? I'm thinking of something like blue gin but better dressed and a little less trashy-pretentious. Laid back, but stylish, where a man can drink happily and possibly dance in a penguin suit... But I'm at a loss. Thoughts?

Dan's Cafe. The perfect night cap.

Actually, Indebleu is a good idea, and I've never been to Zola. We'll probably head that way and see how we feel.

One problem I have with DC is that I feel like cool nightlife options are extremely limited. Especially on weekends, most places are either fratboy stuffed or terrible dance clubs. There are few cool gentlemen's bars where you can air out and talk, and few cool lounges.

It's a conundrum. Indeed, the EuroJack crowd is a huge issue. I've not been to Lima except for dinner--it might be a possibility. I like Science Club, but I don't think it quite has the ambience I'm looking for. The Hay Adams is a great place, but also not ideal, since it's not all that happening.

Of course, we'll have fun no matter where we go, and as long as you don't let yourself feel out of place by carrying yourself as if you were still someplace more formal, it doesn't matter all that much.