We live about an hour away and usually fly out of Dulles when we travel, and often leave early in the morning so there is always anxiety about getting to the airport on time, traffic, etc. Plus the cost of long term parking!
This time we went down the night before and stayed at Homewood Suites. Honestly it was a no-brainer! You can park there for free while you're gone, and they have a free shuttle service to the airport and back. So basically for the cost of long term parking, you can get a hotel room the night before, enjoy the free food, and relax and not worry about fighting through traffic to get to the airport on time.
Note that the shuttles don't run constantly, you have to call for one when you get back, so there's a chance you could wait 10-15 minutes...and then if the driver gets a call that someone else needs a ride too, you might end up waiting more for that person to get to the van. We lucked out, the van happened to be at the airport with some other people so we hopped right on. I could tell the other people had been waiting for a while and they weren't too happy; but I guess that's just the risk you take.
Other than the shuttle service, not really much else to say. Homewood Suites is our favorite hotel chain, they tend to be reasonably priced and very large and comfortable. Nice comfortable mattresses too.