Not sure if anyone else has noticed, but the upgradeable flight arrow seems to be broken on aircanada.com. It is supposed to show up next to the flights with availability when you click 'Display only fares eligible for upgrade'. However, they do seem to have removed the Latitude bait and switch that only showed the highest latitude fares when you asked for upgradeable fares. So perhaps I'm expecting too much.

With I class not showing on all of the free sites, I've had to call the SE line to find out which flights actually have upgrade space, or work on the rule of thumb that I=Z most of the time.