I agree, particularly as to the small towns. I recommend St. Sauveur, not far from Montreal in the Laurentides mountains. I am sure there are others, but this is my favorite among all small towns that can be reached within an hour drive of Montreal.
Regarding the subway, I would add that the Lionel Groulx station was used in the movies "The Jackal" and "Catch me if you Can." In The Jackal, it was purported to represent Metro Center station in Washington DC.
Contrecœur, St-Hyacinthe, Chambly, Salaberry-de-Valleyfield on the South Shore, L'Assomption, Ste-Thérèse, St-Eustache on the North Shore are the ones I visited and really liked, and they are all accessible by public transit. Most of them are not far from highways either. Rigaud is really nice too but driving is recommended. I prefer these small towns over the touristy part of Québec City.
I believe Radisson also appeared in some movies and its brutalist architecture is quite unique, but it's quite far from downtown and there isn't much interesting stuff around, other than the traffic jam on A25 near LaFontaine tunnel... One time I visited half of the blue line stations by walking to the next station then taking train to the next station and repeat. The area from Côte-des-Neiges to Outremont is quite nice to walk around and there are many interesting shops and restaurants in Outremont and along Jean-Talon.