One thing I would definitely suggest is for you to bring your bicycles and hit the bike trail between Montreal Old Port and the town of Lachine (12 miles West). The trail follows Lake St-Louis and St Lawrence river.
I lived in that area (town of Dorval) all my life before moving to the States in 2005. I used to bike from home to the Old Port, have lunch and come back. If ever you do that bike ride, don't miss the peninsula in Lachine....a gem with modern architecture.(bring a picnic)
Also, while in Montreal, go visit St-Joseph Shrine on top of Mont Royal, and take the trail to the top of the mountain where you will have spectacular view of Montreal. While in the area, take a car ride to Cote des Neiges cemetery which is the one and only cemetery in Montreal (Millions of people are buried there)...... It even has street names!
