It's been a LONG time since I've been to Toronto.
CN Tower is a must.
There are some nice market/shopping areas, but I forget the names.
I've never been to it, but there's a castle of sorts right in town. I forgot the name so I googled it: Casa Loma. Looks interesting.
Although it's been more than a decade since my last visit, my memory of Toronto was not of a world class Canadian city, but rather of a modern city with worldwide influences.
If it were me, I'd jump over to trip advisor and see what other folks liked/hated.
Have fun.