Numi,
I'm not from Montreal but I've been there a bunch of times. Try the the loop from Crescent, along Ste-Catherine over to Peel. A few good spots on Crescent. Fun mixed with pretention. Spots like Thursday's, Electric Avenue, Newtown (Jacques Villeneuve's club - Newtown is English for Villeneuve) are all on Crescent and are fun on the right night. A lot of good restaurants around their too. Weinstein & Gavino is good Italian. I wouldn't recommend Newtown for food though, pricey for what you get. If you like a good steak, try Gibby's in the old part of the city. On the pricey side but fantastic. There is a good Thai place on the corner of Crescent and Ste-Catherine also. Great food good prices. Great rib place, the Bar-B-Barn on Guy also (maybe not for a trip with the lady though).
Hope this helps. Have fun.