I live in the urbs and work in the suburbs. About half the route is along busy city streets (some with bike lanes) but where traffic speed is relatively slow due to congestion. (Bloor, Queen, College etc.) In the summer I ride through a ravine park for most of the second half of the route. In less pleasant weather, I either take suburban residential streets for the second half, or park my bike at a subway station to continue the commute from there.
I found getting an odometer last May to be a great motivator to increase the amount I spend commuting by bicycle instead of transit. From May to December I rode 2000 km. Since my trip now is longer I don't always commute by bike but almost always commute by bike for errands and shopping within downtown. The nice thing about Toronto is there is lots of bicycle parking and other cyclists (though when they aren't obeying the rules of the road and/or are very slow, they are sometimes irritating!)