My home town!
Super Sexe is a MUST.
If you appreciate a good smoked meat sandwich, Schwarts on St. Laurent is also a must. In fact, if you've never been, you should go just so you can say you have been.
The old city is really nice. a few decent restraurants down there, but it's very touristy. If you want something incredibly fun to do, check out Saute Moutons. They take you out in a big jet boat through the lachine rapids. lots of fun. If you want something that doesnt take as long and costs less, there's another jet boat that just takes your around the st lawrence doing spins and stuff. also fun.
I would normally tell people to stay away from Cresent St.. filled with uber lame bars/clubs, lots of youngins from the states and straight edged peeps. But then again, that might be your thing, if it is, check it out. Lots of good food on st laurent and some okay lounges. Also some good hipster spots up on the plateau.
Time super club on St Jacques is a good time.
If you want to keep the party going late night, Stereo is a dope afterhours. Mixed crowd though. Another decent afterhours is Circus. No booze, party doesnt' get going until about 3am and goes until anywhere from 10am-noon or later depending on the DJ.
If you're in town on Sunday, Mount Royal Park for the Tam Tams is def a must for someone that has never been. It's basically a massive drum circle. I've been there and seen thousands of people in multiple circles on nice days.
Sunday afternoon.. Piknik Electronik is also amazing. HUGE outdoor party on the water, and free! Booze is served. Guest international DJs. on nice days there are thousands of people there.