If they have a rental car, they can drive up to Lockport and take the Erie Canal locks tour.
http://lockportlocks.com/cruisesch.html
https://www.youtube.com/watch?v=ZPTnMPnAi4Q
One of the biggest disappointmants of my life was my trip there.It looks exactly like every picture or movie you have ever seen.After 5 minutes I was bored to tears.I cant imagine spending 4 days there.