My husband and I live in Maryland and had an 8 AM flight from Dulles in Herndon, VA. The night before we were to leave, my sister mentioned that she had stayed at a hotel nearby and was able to leave her car there rather than pay for daily parking at Dulles. Since we were going away for 2 weeks, we decided to call and we made a reservation on the spot. The 'Park, Sleep, Fly' deal was perfect for us.
Yes, it would have cost less if we had only paid for parking for two weeks but by staying here we got a head start on our vacation by staying at a very nice hotel. Even more important though was the immediate stress relief of knowing we wouldn't run into any traffic problems to make us late nor would we have to wait at the airport for hours because we were too early.
We took advantage of the free coffee in the morning (alas, our flight was delayed until noon!). The staff was professional, the bed very comfortable. The shuttle was convenient and the driver very friendly. I would definitely recommend the hotel and the 'Park, Sleep, Fly' deal if that suits your needs.