I rode the Erie Canal last year and I think you'll enjoy yourself. The route is obviously flat and the surface is good hard packed gravel in most places. I found 25mm to be ok, but for comfort you might want to go with 28mm or higher. There were some sections that were under construction so I had to carry my bike. Riding from Buffalo to Albany you'll have the prevailing wind at your back. I was dumb enough to ride in the other direction and the day from Rochester to Niagara Falls was tough as I was riding straight into the wind coming of Lake Erie
uhm, Rochester to Niagara Falls? That's a damn long ways...
First time I tried the ride, the canal had stones the size of grapefruit... 3 tubes and 2 wheel true-ings. I ran out of tubes... The local bike store was closed 20 minutes before I carried my bike to it... Hey on you bike or under it... right? But that was '97....
The ride is quite nice now...