Ah, Montreal. Probably my favourite city I've ever been to. The old port is mostly full of smaller b&b's - if that's your thing then you'll have no problem finding one. A favourite of my parents' when they used to visit me there is the Auberge Les Bons Matins (
www.bonsmatins.com). It's kind of a trendy, funky place, with lots of bright colours. It's classified as a B&B, but it's a rather large one. They have probably about 15 or 20 guest rooms in 2 or 3 buildings (all adjoined). They make a damn fine breakfast, too. It's a bit out of the way if you're on foot, on a quiet residential street, but less than 5 minute walk to the subway. Then again, by "a bit out of the way", I mean that it would be a 20 minute walk to McGill, 5-10 to the Bell Centre, maybe 20-30 to the Palais de Congres.
Hope this helps.
Chris