Staying at Val's place was my best Airbnb experience so far. Val was kind enough to pick us up from the subway station with her car, give us a very clean and neat place to stay and get muffins and orange juice for our breakfast. The place was huge and very nice with brandnew furniture and a hotel quality bathroom. She has this folder in which you can find all the important phone numbers and information about the house (such as the wireless password) along with the leaflets of the restaurants in her area. I think all the airbnb hosts should follow this example.
As long as you don't mind staying in the basement level, I don't think you can find any other place to beat Val's. I know where I am going to stay in my next visit to DC and I highly recommend it to everyone!