Another possibility if you want to ride along the Miss. River is to ride ACA Transamerica to Chester, IL. Ride north along the river to St. Louis. From St. Louis there is a nice road that takes you through Centralia, IL into southern Indiana. Crossing Indiana in the south you end in Madison, IN (beautiful). Then north of cincinnati pick up the bike trail that runs north to Fairborn, OH. Make a way west in southern OH (lots of hills) into southern PA. Along RT 30 (hilly) to Gettysburg and a little history. Head to Jim Thorpe, PA and the Delaware Water Gap. You can pick up the Atlantic Coast Route from there and follow it to Sutton, MA. From Sutton, MA I have a very nice route to the Cape that I could email you if you want it.
Hope this helps. I would be happy to provide more info if you want this sort of route.