It was really nice to stay at Roses and Billys House. They were very helpful and gave us a lot of advises for our sightseeing plannings. The rooms where just great. The bed was comfortable and everything was clean. One of our best places so far.
If you are thinking about renting a car for the time staying in Washington: Don't do it, the metro is nearby and very fast. Even a supermarket is within a five minute walk.