Mount Vernon Trail will probably be pretty crowded. If you want to avoid the worst of it, take the W&OD to Shirlington, cross the pedestrian bridge to the 4 Mile Run trail. At route 1 cross over to the south side of 4MR and take Commonwealth to Old Town, then cut over to the river and continue with the MVT. If traffic is not bad you could ride the parkway instead of the trail, or south of ****'s Marsh cross to the other side and take the residential streets as far as Fort Hunt.
W&OD to Reston would be easy. Maybe too easy. If you are early enough, make a detour to Falls Church farmer's market. (One of the better ones in the area. I picked up some great apples there last weekend)
Or Custis into DC and C&O out to Great Falls and MacArthur back to DC. Makes a nice loop.
Or go into Georgetown, ride up Wisconsin Ave all the way to Bethesda, switch to the Georgetown Branch and Jones Mill / Beach Drive as far as you fell like going. Could also use the CCT instead of Wisconsin but the crowds will be heavy. Maybe CCT up and Wisconsin back. Or back on Beach Drive thru Rock Creek and take one of the many roads out of the valley.
For me...I'm headed for Loudoun County this weekend. Find me some hills.
Last edited by cc_rider; 08-22-08 at 08:32 AM.