We had great experience at Adam and Jen's. Adam and Jen were very nice and helpful, and supplied us with a lot of information about DC and how to make the most of our time there. The appartment was small but very comfortable and clean, and even came with a generous assortement of drinks and snacks. In order to get around, a 15 minute walk will get you to a metro station and from there you can easily get to anywhere in DC.
All in all it was a great time and is highly recommended.