It has been a long time since I was last in Toronto, but I've always really loved the city. You may want to take a look at the official City of Toronto website here: Toronto - The official City of Toronto website It has quite a bit of information about the public transit system (including the excellent subway system which runs into some of the suburban areas).

Unfortunately, it appears that Toronto Transit is currently on strike - but I guess that happens in most big cities these days.

And for getting out and about on weekends, check out Toronto Island Park - it's a big parkland located on islands out in the lake, just a ferry ride away from "downtown" Toronto.
Cheers,
Bev