There are definitely some hairy intersections - watch particularly the Hunters Mill intersection around the 14 mile marker. There have been people I think killed there in the past year (I think it was that intersection). The road is twisty, so you can't see far in either direction. Also, the people that drive that road don't seem to understand the concept of a crosswalk.

All in all, it's doable if somewhat long. Do bear in mind that the first 12 miles from the Potomac into Virginia are pretty much uphill, so that may be an issue depending on your tolerance for hills. The hill up to 495 is particularly fun.

All in all, though, it's a rather pleasant ride. If you can do the miles day after day, I'd do it.