…for three days, or thereabouts, with my dad for a birthday trip (July 15-17). I’ve got all the main tourist places scouted–Musee des Beaux-Arts, Biodome, the Science Centre–but tell me, you Realdopers, where should Dad and I really be going? 
The Just For Laughs Festival is July 14-24, so you can probably catch a show somewhere if that’s something that interests you.
There’s also fireworks that Saturday at LaRonde. You can see them from Old Montreal, or the Jacques-Cartier bridge, or spend a day at LaRonde on roller coasters and stay for the show.
The Notre-Dame Basilica is incredible! So warm and grand on the inside. I lit a candle in honor of all of my Catholic friends. Check out Le Biodome one afternoon. It’s a charming biosphere holding jungle, forest, artic, and seaside habitats.
If you need a place to stay, I highly recommend the Auberge Maeva hostel. Clean and safe, with the nicest staff. You’ll meet some fascinating people.
Go shopping, I was only in Montreal for 2 days and didnt really do a lot, but I did notice they had a lot of nice shops on Catherines Street (I think it was called Catherines Street).
If you like Formula One, you could go see the race track, theres not a whole lot there though.
There is a hill that looks over the city of montreal, the view from it is spectacular. The whole city is laid outin front of you.
LaRonde looked like fun but unfortunately it was closed while we were there.
The old city, of course. Wonder through the alley ways and see the local artist display their stuff. Have lunch or dinner on one of the outdoor patios. For a neat dinner treat, head up to Prince Arthur which is closed to traffic and has BYOB restaurants with reasonably good food and fun atmosphere. If you run out of wine during the meal you can just hop accross the cobbled street to the wine shop (depaneur).
Drive north an hour and a half to Mt. Tremblant ski resort. It’s really quite something even in the summer with it’s Swiss style village at the base of the mountain.
Or simply stroll and shop along St.Catherine between Bishop and St. Laurent blvd. It’s a real mix of campy and trendy shops. Eat a quick shawarma or shish touk sammy from Basha’s. Yeah, it’s campy but way under-rated by locals. Also Kojax for greasy but yummy gyros.
For a Queen Street West flavour, you can walk along St. Laurent Blvd north from St. Catherine for quite some time. You’ll go past Prince Arthur on the way and see a real mix of Old European type shops and delies along with more current and trendy clothes, book, novelty and kitch shops.
Of course, the cathedrals, museums and attractions mentioned in above posts are also worth while. I guess a lot depends on your mood, priorities and time. It’s a lot to cover in 2 or 3 days so be prepared to get out early and go all day to cover as much as you can.