More details appear on the amenity lists associated with the trial maps.
Use these itineraries as starting points for your own planning. This is the itinerary of Yokatomactrek '99, June 1999, the inaugural trip of the Allegheny Trail Alliance. The van wasn't large enough to carry all the riders and bikes, so we selected lodging within easy biking distance of the trail. You could certainly start in Washington DC instead. Let someone else do the driving.