You are probably too late for most decent places at this point, but our top 3...
* Affectionate Pet Care (Fairfax Station)
* Companion Animal Hospital (Burke/Fairfax Station)
* Paws A While (Warrenton)
http://www.pawsawhilepetmotel.com/
The nuns are terrific, but we only use them if we are going away for at least 5 days since it is so far away. Very caring place with large, clean runs and lots of extra services.