Expensive but nice
My husband and I recently had meetings at the Hyatt Regency, and we thought it was a nice hotel. The location was great for sight-seeing -- we were able to walk to the Mall and the Smithsonian museums and jog to the White House and Tidal Basin to see the cherry blossoms. The staff was also excellent. High marks to the staff outside, who always got us a taxi quickly.
We give five stars to this hotel for their convention facilities. The meeting rooms were large and well-appointed, and the main ballroom was beautiful.
Unfortunately, the Hyatt was pricey at $299 for a convention rate. Our room was pretty standard for that price. I haven't been to DC before, though, so cannot compare to other local hotels.