My boyfriend was working for a client in Montreal in May and is back there now for some followup work. I spent a long weekend with him in May...
The Saute Moutons Jet Boat ride is amazing!!! This is a don't miss treat.

Sit in the front.
The client put him up in the Sheraton, which is pretty nice with a cool lounge. They don't have hot breakfast, but the continental options available are pretty good. Comfy beds, good views, good access to the Metro. If staying for fun though, I would recommend something closer to Vieux Montreal.
Basilisque Notre Dame is very pretty, and the nearby square in front of Hotel de Ville is a good place to hang out, with lots of street performers. Off of this square (Rue Saint Jacques?) there are tons of restaurants, mostly a bit touristy... But I liked that they all had lobster specials. We ate at one or two of these places with mixed results.
Some of my best experiences were simply getting way out into the neighborhoods to shop for some of the items I miss from France that aren't easily obtainable for me in the US (even with Central Market and Whole Foods being based here in Austin), like unpasturized cheese and sausicon. I had a great adventure making my way across town to Fromagerie Hamel, where the wonderful cheese monger picked out some great items for me to fulfill my cravings. He as even able to vacuum seal them for me.

I felt like Arlo Guthrie Coming into Los Angeles. Behind the Fromagerie Hamel there's a huge market for produce, flowers, etc. Very convenient for picnicing.
Oh- They also have a Zara in Montreal. I always stop in Zara whenever I'm in a city with one. Didn't find anything I liked this time. Seems like the quality may have suffered a bit since my last visit.
Lots to see, do, buy and eat there. Be sure to do the Jet Boat tour!