Paulie from Knoxville TN on 7/15/2008 8:28:56 AM:
I havent had a chance to ride the GAP(Pitts PA to Cumberland MD) yet but I have done the entire C & O Canal trail(Cumberland to DC)You will find the Katy very similar to the C & O. The Katy is maintained better and has more options on lodging and food.
The Katy only uses the road in a few places-Sedalia and maybe a little in Boonville(somebody correct me if I"m wrong)but its brief and the street is marked.
The elevation on the Katy is no biggie, I still call it flat even though there has been some debate on this site about the issue.
Paulie