I'm just returning home from 4 days in Montreal. I've spent a lot of time on rails! Regional GO trains to/from Toronto Union, then national Via Rail to/from Montreal. In Montreal it was the Métro subway, which technically runs on rubber wheels but is still guided by tracks.

Other than that, it was a loooooot of walking. And Montreal certainly has some variable altitude to it. Still, it was refreshing to not have to deal with driving a car.