For Ontario:
Sightseeing in Toronto 1 or 2 days (go up the CN Tower)
Niagara - 1 day incl Maid of the Mist
Niagara on the lake (not the same as Niagara) 1/2 day, then a wine tour 1/2 day (know the kids can't drink it but it is interesting, especially the special type of wine they make - won't spoil it by telling you). There are cranberry tours elsewhere if your non-drinkers.
3 days camping in Pinery Park on Grand Bend. Spent an amazing summer there. On a clear night, scorching summer (it does get really hot in Canada in summer, especially in the centre of the country), evening cool off in the lake, sat on the beach and all I could see was thousands and thousands of stars. It was like nothing else I'd ever seen.
Plus there is loads of outdoor stuff and they are really geared up for it. Algonquin Park has canoeing and trails and all sorts of stuff.
Plus loads of places have summer festivals. Canada Day is always fun.
I've heard nice things about Vancouver but not lucky enough to have been.
Have a great time, I've been 3 times and loved it. I'd go more often if I could. Beautiful country and the people are lovely.