Ugh, I'd never ride on Spadina! Way too busy. Have you tried the bike lane on St. George, Beverly and down? It's route 35 on map 10. http://www.toronto.ca/cycling/map/index.htm

If you really want to avoid riding on city streets, why won't you take a Bathurst bus as far south as it goes? That's what the racks are for, why not use them?

Also, try looking up some routes here: http://www.ridethecity.com/toronto

For a longer ride, you could take the subway (you will be fine taking your bike on in off peak hours) to Royal York and take the Humber trail south to the lake and across going east. Nice ride.