I ve never stayed there, but I have to believe the Americana Hotel in Arlington, Virginia would be a good choice. It s right on the main drag that goes to the National Airport and whatnot. See link below.
Helix is good. Most hotels have party and reception rooms that include a bedroom, a living/dining area and bar with a small kitchen. These are typically situated on the end of the hallway where there will be as little disturbance of other guests as possible. Just let the hotel know what you want and they ll do their best to accomodate you. You are generally charged the same rate as any other suite costs.
the best one...the name escapes me...is in arlington! even though its def. not DC, it was the ****