Great Hotel
My wife and I stayed at the Fairfax in early November for our anniversary and had a great time. The hotel is in a great location. It felt safe and was close to the dupont circle metro station and some nice restaurants (including the one in the hotel).
The conceirge and staff were very helpful with great restaurant recommendations, tips, and a different set of pillows for my picky wife. We had drinks and food in the lounge downstairs, which was wonderful (although the server could have used a lesson on friendliness). 
The room was a little smaller than I'd expected and faced an alley instead of the street, but it was comfortable, clean, and what we needed. I'd suggest if you were going to stay in the hotel for extended periods of time to upgrade from the basic room. 
One thing I need to say (and this is applicable to all hotels) is: What's the deal with charging guests for wireless internet? This is nothing against this hotel, because it seems like all hotels in larger cities or above a certain price do it. You can get free wireless at cheap hotels or even at the McDonald's, but when you stay at a 5 star hotel you need to pay for it? It doesn't make sense to me.
Overall, for the price we paid (which was lower than most hotels in the city actually), this was a great stay and I would highly recommend.