We're going to do a 3 1/2 day bike trip up the C and O Canal Towpath trail (183 miles) from DC to Cumberland, MD from 24 to 27 July, staying overnights at campsites along the Canal.... The plan is to leave the DC area Thursday after work and do about 20 miles on Thursday, about 60 miles (each) on Fri and Sat, and the remaining 40 miles or so on Sunday. From Cumberland we will catch a ride (pre-arranged outfitter) back to DC, so that we will be home at a reasonable time for work/school the next day.
I have done this trip 4.5 times, and it is a delightful bike trip.... the path is level (except for 10 ft rises at each lock) and is packed dirt/gravel... yes, you are in the woods pretty much the whole time, which is nice, but there are small towns every 30 miles or so where you can eat or restock. The Canal is a National Historical Park, so it is well maintained and there are hiker/biker campsites (clearing with well water pump, porta-potty, picnic table, and fire pit) every 10 miles or so. Additionally, there are many interesting natural/historical sites along the canal that make for a fun break from biking.
For this trip, mostly Co-ops are going to come, but others are invited.