This is how I spent a couple hours this morning. Got up at 5 per usual, makes for a nice timeto be out. Beautiful day. Arlington, GW Parkway, Potomac, Point of Rocks, Leesburg, Middleburg, The Plains, Manassas, and back.
The GW Parkway and Clara Barton Parkway are nice as usual. The area between Potomac and Point of Rocks MD is full of nice little roads, lots of side detours, and even 28 is nice. Middleburg and Leesburg VA are great for stopping for a coffee (and inevitably chatting with strangers). Halfway Rd between Middleburg and The Plains is twisty and fun. The Plains to Manassas is nice on the back roads. 66 is a relative drag but its better than the sprawl thats on most of the other routes.
I take a general route like this a lot, sometimes crossing on White's Ferry, sometimes staying more North in VA on Georgetown Pike. Its a nice set of options for rides of varying lengths, right around DC.
P.S. Did I mention I love my bike?