I've taken Amtrak up the Hudson many times, but never into the Adirondacks. That does sound like a very long time to be on the train. Would you consider perhaps flying one way, and taking the train the other? I'm seeing LGA-YUL one-way fares of just $98 on most May dates (but that's probably for Basic Economy). There are mileage redemptions available on some dates for about 8,000 miles per passenger, as well.