My ideas:
Option 1 - straight down Yonge St. The nasty part in my opinion is right close to home for you at the on ramp north of the 401 and, even worse, the off ramp south of the 401. The hill you can live with and the rest of Yonge St isn't too bad really. You could cut over to Mt Pleasant at Lawrence, it's not bad for going south.
Option 2 - Head west to Bathurst, south to Armour Heights( just south of the Earl Bales park) then cut through the residential area to get to the top of Avenue and go south from there. I haven't ridden Avenue south in the morning rush. I imagine it might be slower than the evening rush. (Avenue and Lyttons was the site of a fatal collision a year or two back. Experienced cyclist and a dump truck, just FYI )
Option 3 - Combination. Use option2 to get to Avenue, get over the 401, then head one block east on Wilson to Yonge blvd and head south-east on it (cutting the corner on Hogs Hollow) to get to Yonge St. Traffic going down Yonge Blvd won't like ya 'cause it's tight to pass a cyclist, but there ya go.

I've used all of those routes quite often, but pretty much always in the evening. Bathurst St. (south of the 401) I avoid at all costs, but that's mostly because of the older drivers who seem to use it. It might be an option for the morning commute though.
That's all that I've really got any experience with. There might be something to the east but someone else'll have to let you know about it.
Cheers, Dave