Just happened into this thread (I've been keeping away from BF to try and not get the urge to ride outdoors while I'm still recovering from a serious skiing injury).
Last June, a friend of mine and I did a one-day press of the C&O, from Cumberland to DC. We didn't quite do the whole length, skipping the section from Great Falls to the last mile in Georgetown due to fatigue and the fact that we had both ridden said stretch many times before. But it was an epic day in the saddle, for sure!
cycling log: 29 june 2013 (c&o canal end-to-end) | randomduck
FYI: we did a one-way car rental from DC to Cumberland as our means of transporting our bikes and gear to the trailhead. That worked quite well.