I quite dislike the Hyatt House Herndon. Had to stay there during the big snowstorm a couple of years ago and realized when I pulled in that it's an old exterior-access Summerfield property... don't like having to schlep luggage up two flights of stairs to get to my room. (Even worse during a foot of snow!)

I am partial to the Hyatt Dulles, it appears from the floor maps that every room is a junior suite and the rates are often $71 on weekends. The HP down the street is perfectly acceptable if you're just going to sleep. The Hyatt Reston has the Town Center which is really convenient if you don't have a car. (The Hyatt Dulles does have a shuttle 2-3x/evening over to the Town Center, however.)

I've not been to the Fair Lakes property, but it is not what I would consider particularly close to the airport, at least 15 minutes with no traffic.