I've been to Quebec City and Montreal - never to the country side though really ... if I went back again I'd definitely look to rent a car or something and head out of the cities - up to the mountains etc.
Montreal and Quebec city are very different types of places but both very interesting cities to visit.
Quebec City must be almost unique in North America for having an old town centre in the european style with intact fortifications ... it has a very European feel indeed to it.
Montreal is a much more North American city in appearance - it's a very cosmopolitan city with a lot going on .. it has the most unbelievable number of restaurants also!
George Hook on newstalk106 does an very good programme on travel. Send an email to them at info@newstalk106.ie telling them where you are going and they will send you a factsheet which covers hotels restaurants must see places etc