If you're seriously thinking about moving there, you need to visit Montreal at it's worst, between mid-November and mid-February, to try out the weather. (I was in the city for a week once in late November and discovered for the first time what "chilled to the bone" meant, and the sky was also consistently, monotonously gray.) After that you need to experience July and August, all humidity and mosquitos. (I also visited once in August and felt like I needed four showers a day.) I understand from friends who've lived there--and I've had a number of them--that the town is best in Spring, when the sun finally shines again and the city warms up and everyone is out on the streets celebrating. (I bet it's like Helsinki in that way, almost manic in its brief pursuit of pleasure.) But making a life in a particular city rarely affords the luxury of avoiding the bad days and experiencing only the good ones...
San Francisco and the Bay Area? The climate's good enough (or at least not bad enough in certain areas) that weather need not be a deal-breaker the way it is in Montreal. I did both undergraduate and graduate work in the Bay Area, and spent a couple of summers working in San Francisco. These days I visit the Peninsula (south of the city) on business for a couple of days each month. The whole area from Marin across the Bay down to Santa Cruz can be extraordinarily beautiful and it can be an immensely satisfying and exciting place. It can also be smug, self-satisfied, sanctimonious and hugely (let me write that again, hugely) provincial, which is why, after grad school, I chose not to stay. I have friends who love it there, and who wouldn't live anyplace else. But for me, I'd rather just visit.