Depends on what size boat you have.
If a sailor, going north, you would be distepping at Catskill. Stepping at North Tonawonda. If going in reverse, the reverse.
Have handled a 45 footer singly thru a few locks, but was not a happy thing - the lock lines don''t reach well. I would think that anything up to a 35 would be nice. Depends upon your prep, of course. Use boards and I would think you would be fine.
Again, the people at Hop-O-Nose Marina in the catskills are fantastic,like the food in the little bar, as are the guys at the "marina" in North Tonawonda. And, when you go to the "marina" in N. Tonawonda, if they are still makin that cleaner, pick up a few gallons. It works great for everything from tannic stains to spider poop without taking your wax off or harming the gelcoat. Sorry I don''t recall names, but I''ve slept since then.
I recall walking into a tiny bar in N. Tonawonda (you have to walk up the grassy side of the canal and then left down the street) and seeing the tv on and hearing the regulars cuss because they were interrupting the basketball game. What was on was the O.J. chase in his bronco - they had the ball game on in a tiny corner of the screen.
Anyway, wonderful, helpful people in both places, so don''t worry, you will not be alone.