There's a shortage of decent budget accommodation in the metro DC area, and the Wolf Trap is a good choice if you're on a budget. It's about a mile from Vienna Metro station which takes about 40 minutes to downtown DC (and the all day parking does now accept non-US credit cards on exit).
The Wolf Trap itself is a typical 70s motel, with external corridors on 3 floors, but generally quite well maintained. There's a fair bit of traffic noise from Route 123, but it's acceptable, and as the only heating is through the room a/c units, if arrive late on a cold or snowy night (as I did), the rooms can be cold, but soon warm up reasonably well. Breakfast is simple (bagels, donuts and fruit) but adequate and included in the rates. The high speed internet access works OK and is free but sometimes needs resetting by reception to work. And there's a terminal in reception at which you can print off airline boarding passes, etc.

I have been staying at the Vienna Wolf Trap every time I have visited the Washington DC area since early November of 2009. It is the only accommodations I use. Their rates are extremely reasonable (sometimes I stay for month-long periods) and every member of staff that I have encountered has been amiable and professional. Any issues which may arise, such as problems with internet, etc. have always... been speedily remedied by the front office. The Wolf Trap is located in a safe, clean suburban area which offers several restaurant choices as well as grocery and convenient stores, all within walking distance. Public transportation is also easily accessible. Although these accommodations cannot be considered "luxury," if you can be satisfied with a clean, comfortable room in a tranquil area, then this place should be your first pick.

We stayed here for the final night of our holiday, the location was great, only 1 mile from the metro station with trains going into Washington DC. Also only about 20 mins from Dullas Airport wher we were flying out of.
The hotel was tatty at the best. Laminate broken off the doors, tape on window cracks and towels like sandpaper. There were cigarette burns on the bathand everything was very worn. It was clean
, we checked the sheets and pillows. We did stay only because we couldnt find anything else nearby. We really wished we had researched the location before leaving the UK.
It was probably a nice hotel in the 70s, shame it hasn't been looked after as the location is great

In all honesty, we actually didn't stay. The exterior was run-down and a bit sketchy, but we decided to try the room. I've easily stayed in over 100 hotels in my life and have NEVER seen one in this state! Room odor, holes in the walls, floor "spongy" to walk on, mold in bathroom (that had signs of flooding/water damage), it was absolutely gross! I looked as close as I did out of morbid curiosity. My wife said the odor of the room lingered in her nose for some time after we left. Much to their credit, the office staff were friendly and never questioned our room refusal.