I spent one night in the DC lounge & would recommend it - but check to be sure its open the night you're there. I was really able to snooze there... the few folks that were there didn't care that I cut off the TV.

On an other occasion I spent I also spent a night (accompanied by my girl friend) in an all-night restaurant bar on the upper level of the International terminal (outside of customs). Semi-comfortable couches. At the other end of that level some folks were crashed on the floor near the restrooms.

I posted a more detailed answer under the LP-Who's Really Going thread so you may want to check there for more detail.

Hiker Guy