The Americana is in Crystal City, close to (Reagan) National Airport
It sounds like you'll be doing some siteseeing while you're here. To save a bit of money on admission tickets, bookmark the DC site on Groupon to see if there's anything of interest, as well as Goldstar. Over Thanksgiving weekend, I was able to take family members to Mount Vernon for $7 instead of the usual $15 (Groupon), and the Museum of Crime and Punishment for $10 (Goldstar). Mt. Vernon's recently added an orientation center and separate museum that are definitely worth seeing. Don't be scared off by the big sign saying "Education Center" - it's entertaining.
The Smithsonian museums are free, but if you go out to the Air and Space (the Udvar Hazy annex) facility that's way out by Dulles airport, parking is $15. Locals know that parking is free there after 4 pm, and the museum's open until 5. That gives you an hour, which is about the right amount of time to spend there if you aren't an aeronautics buff.
And major word of warning: our traffic is terrible. The Interstate Beltway 495, is undergoing major construction in Virginia. I don't recommend anyone to take it when it's dark or raining. Be sure to stop at every red light and observe the posted speed in DC - they've got cameras everywhere. It's a good idea to take the Metro into DC, since parking is scarce, and the city brings out fleets of tow trucks to haul away parked cars beginning at four pm along certain routes.