Hi Zion, just back from DC and stayed in a great place.. Embassy Suites at the convention centre around 10th street. Very close to everything, great staff.. free bar to all residents each night for 2 hours! breakfast included - best breakfast I've seen. Rooms were huge suites and worked out to be about 120euro for 2 of us per night.
I stayed in the Hyatt Regency (its near Capitol Hill and Union Station) and it cost $149 per night + some tax for 2 and includes breakfast. It gets a lot more expensive depending on dates (probably if Senate etc is sitting) but it was really good value, and worth a look. Also, it has a swimming pool etc if you are interested (or have time!) for such things.