For the Eric Canal Bike Trip, I am aware that people may come from lots of different locations (Pittsburgh, New England, DC, and Rochester being the most likely spots), having different transportation needs. Luckily, there are lots of transport options available to us.
Most importantly, there is an actually good Amtrak line that runs the whole length of our trip, from Niagara Falls to Albany, with stops in all the cities along the way. They have several trains a day in either direction, at reasonable times of day. With bike, you have to take the pedals off and put it in a box, but most people should only need to do this once (at the start or end of the trip). There is also the option of renting a car one-way (since there are sizable cities on either end - Buffalo and Albany).
For Pittsburgh folks, I expect the easiest thing to do is to drive to Buffalo (or maybe Rochester), park the car, and take the train to Albany. When you eventually bike back to Buffalo/Rochester, you are at your car. For Rochester people, you can just take the train to Albany on the first day, then bike back. Getting from Buffalo back to Rochester should be easy - either have someone pick you up or just bike back in one additional day (this is my plan right now). For NE/DC folks, you could get a train to Albany or drive there. Either way, you can take the train back there at the end of the trip, then either hop in your car or get another train to your final destination.
In Troy, NY, the meet-up home base will be at my sister's place downtown. She is currently scoping out places that people could park their car for the week (if you want to do that). Troy is a short ride on a bike trial (5 miles) from the Albany Train Station.
In Niagara Falls, we will arrive at mid-day at the end of the trip. This allows for several options: hang around the NF area (there are lots of hotels and camping in the immediate area), go immediately home (the train station is not far (5 miles?) from the falls, or bike back towards Rochester. Note: if you want to go to the Canadian side (and you probably do), get your passport ready (Also, passing customs on a bike is lots of fun).