Great Location for Business of Pleasure
I stayed two nights at the Hyatt for a lobbying effort with medical students. About 1000 medical students were in attendance and most packed rooms in this hotel. The Hyatt staff were very attentive. Check in was efficient, and the rooms were excellent. Beds were nice, room was clean, and bathrooms were spacious. Wireless internet worked well. It stated that there was a $16.99 per day charge for internet, but they did not include this on my bill (I am a Hyatt Gold Passport member, so this may be free with that). The upside of this hotel is its location - literally two blocks away from the U.S. Capitol. After holding a meeting with over 1000 participants in the Hyatt Conference room (good breakfast provided and AV equipment worked without a hitch), we all headed over to lobby congress on medical issues. The proximity of the hotel to the Capitol and legislative buildings made the trip worthwhile. It is also only 3 blocks from Union station so it was easy to take the subway back and forth from Reagan International Airport. There is a nice bar and restaurant in the lobby, although I didn't eat there - these were nice places to gather. 
The downside of this hotel was the noise. I could hear the people talking in the rooms on either side of me and I could hear the elevator 'binging' every time it opened on the floor. I'm glad I had earplugs with me. 
This is an expensive hotel with a great location and really good service. The noise prevented me from giving it five stars, but I would still highly recommend it.