We stayed at Sonder (DC) for 5 nights and had a wonderful time. The location is fantastic: the residence is ideally located close to restaurants, the famous monument mall and everything best that DC hast to offer. The bathroom was well provided, the apartment clean, and the wifi fast enough to work. Finally, the gym was modern and well-furnished -- much better than what I have seen in traditional hotels.
Our only slight disappointment was with the pull-out couch. The mattress was thin and uncomfortable, and the blinds quite transparent making it a little difficult to sleep in the living room. Not a huge deal but something to keep in mind if you are planning to sleep here for several nights with a group of 4 people.