MikeRides

The Erie canal trail is ridiculously flat pretty much the entire way from Mohawk to Schenectady (I started in Utica and had to ride route 5 to the start of the trail). I haven't rode east of Schenectady nor have I rode west of Utica yet. Like DCwom said, traffic is pretty light and for the most part the shoulder is plenty wide on route 5 S which runs parallel with the canal. The last time I was on this stretch was last September, I remember there were a couple sections of the trail that were swamped and a couple bridges closed due to the Mohawk flooding in June. The trail ends outside of Amsterdam where you'll have no choice but to ride on the road (route 5S), which again has light traffic and wide shoulders -- the traffic mostly consisted of dump trucks as there's an industrial area nearby.

My stepdaughter and I will be shadowing the PTNY group this summer, except we plan to start on the Canadian side of Niagara Falls and skipping Buffalo. We're still planning but the rough idea is to ride to the the Canal trail head and take the trail the whole way (she's only 10, and feels uneasy about riding with traffic).

Bezalel

I did a section (east of Rochester) while riding around Lake Erie. There were plenty of gnats so I'd make sure to bring a bandana next time. Otherwise it was nice and I'd consider doing the full length. At my pace I'd give it 2 weeks.