This is an excellent hotel for a stopover, although feasibly you use it as a base to visit DC. Hotel is quickly reached from Dulles via a complimentary shuttle running every 30 minutes. Check in was quick and friendly. I got a high floor room awya from the elevators. As many have already said the hotel rooms are of suite format meaning a separate living area and and bedroom. The living area had a sofa and an easy chair together with the usual desk and chair. The bathroom was off the entrance lobby and was well equipped and clean. the bedroom was reached through French doors and had a King sized bed with Marriott's great mattress and bedding. Both rooms had air conditioning. one advantage of this hotel over many airport hotels is that the hotel sits in an entertainment/ shopping/ dining area. there is a large multiplex cinema and a really good choice of restaurants from TGFI through Chinese Thai and Indian to American Ribs and Wings and Pizzas. Also there is a large Giant supermarket about 5 minutes walk away for other shopping needs. Breakfast was served next to the lobby and was just OK - it seemed rather limited in comparison to other Marriott buffet breakfasts.
I had a great stay there at the astounding rate of $67 per night. Definitely on my radar for stopovers at Dulles.