If you have time to get to Arlington, there are hills a-plenty. They are not very long, but some are very steep and they are frequent enough to give you a very good workout. The Babes on Bikes website has some cue sheets for hilly rides in north Arlington and McLean.

Closer to you, Stuart Mill Rd has some rollers, not huge but better than nothing, and Birdfoot Lane is a good hill. Also Hunter Station Rd -- head east on the WOD from Reston. At the intersection with Hunter Mill, make a sharp right onto Hunter Station Rd and it will take you up a good hill.