This is a great area for riding.
Since the WOD is so flat, there are a ton of recumbents on the 45 mile trail. There is a great recumbent and folding bike shop along the trail as well.
www.bikesatvienna.com
Bike Washington is a great source for DC information. There is a Bike Washington YAHOO group that is active and quite helpful.
http://bikewashington.org/
Hope to see everyone on the trails!