This is a great place to stay to visit DC. We had a family of 5 (2 adults & 3 older teenagers). Supreme was easy to communicate with and addressed all of our questions and concerns quickly and professionally.
The bathroom is fully equipped and has a great shower head with good water pressure. Stack washer/dryer was great to have, especially for longer stays like ours. Supreme provides what you'd need there as well.
The full kitchen has all the basics you could need, and the Keurig is a nice addition. We gave it a workout.
The beds are comfortable, and the couch converts to a good size bed if needed. Our family of 5 had enough room to not feel cramped. Lots of closet space and drawers are available. You won't need to live out of a suitcase.
The TV (lots of streaming movies to chose from) and computer/printer worked great and the Wi-fi worked flawlessly.
There is an enclosed garage in the back that is great if you have a car. No need to worry about street parking!
Access to the Metro system is pretty good. The Metrorail stops aren't as close as I would have liked, but we ended up using the bus system (#70) to get us where we needed when the subway couldn't do it.
Bonus: you might get a visit from Supreme's friendly grey cat, Shadow. He hung out with us for a while in the evenings. He's pretty good at communicating what he wants.