I did this ride in 2002, one-way was about 215 km including some lame detours, but I started around 7 am in Scarborough and finished in time for dinner in Fort Erie, stopping at what must have been every Tim Hortons along the way.
I used Highway 2 pretty much all the way to Hamilton, then went across HWY-8 and RR-81 through St Catharines, to Queenston, and up the Niagara Parkway.
There were some ********ly busy sections though, there has to be a better way.
Lets see if we can't crash google earth....
http://maps.google.ca/maps?f=d&hl=en...68,2.05719&z=9