If you're really looking for a bargain and willing to drive a bit, I was pretty happy with the TownPlace Suites Gaithersburg. It was probably about 40-45 minutes from central DC in light traffic (you would definitely need a car), but for a category 1 redemption it was a great value. Nearby dining options were pretty good.
I'm actually amazed that Marriott still has category 1 redemption opportunities anywhere near popular metro areas like DC. There's another cat-1 TPS closer to the beltway near Andrews that also looks perfectly acceptable if you are planning to get around by car.