Maybe not to everyone's taste, but we had a good experience at the M Montreal Hostel last year. We're not really "hostel people," but our private room was as nice as we've gotten at any hotel, and the location is excellent (right by the Berri-UQAM Metro station, a crossroads of Metro lines).
If you like maple products, head to the Atwater Market, a short walk from the Lionel-Groulx Metro station. There are lots of places in Montreal to get maple syrup/sugar/candy, but the best prices we saw were at Atwater.
ETA: And a travel tip, if you're taking the bus from the airport into town. Half the buses from the airport terminate at Lionel-Groulx (on the edge of town), and half continue through the city center to Berri-UQAM. If you're going anywhere in the city center, and a bus to Lionel-Groulx is leaving first, you'll be told to wait for the next bus. Do not do this. In fact, regardless of what bus you're on, get off at Lionel-Groulx and take the Metro to your destination. The bus ride through the city center takes forever, and the Metro travels almost exactly the same path in a fraction of the time.