We'd booked this hotel as an overnight stop before an early morning flight from Dulles. There is a Hyatt closer to the airport but it is far inferior to the Reston counterpart.
The Reston location is a short hop from the Dulles Toll Road and has a capacious parking garage where they allow free parking during your trip, in some of our cases 12 days so the savings versus the economy lot are decent. The hotel is a new build, pleasant and quite grand lobby. Standard rooms are of a good size, feel very clean and are nice furnished with very comfortable bed. Usual Hyatt toiletries which I like a lot.
The hotel is part of a pedestrianised area with a number of restaurants and shops including a cinema. All within close walking distance.
Overall our first stay was very good and we have since returned on several occassions. If you could classify it as an airport hotel (they run a shuttle every 30mins) then it is probably the best at Dulles.
I've since become a Hilton HHonors member and stayed regularly enough to attain Gold status with them and despite the number of Hilton family hotels that I've stayed at in the Dulles region I still think the Hyatt Reston is better than all of them. The Hilton's rates are usually excellent though and for my next overnight in the area I've turned down the $275 rate at the Hyatt in favour of $110 at an Embassy Suites. I know which hotel is better though.