Also YUL-DEN
Another one in the MR forum is YUL-DEN-YUL for $350 rt ai, which can be routed via YVR. Total mileage is around 6788, for $0.0516 / mile, or as low as $0.0237 if you are SE and take all bonuses into account for 14796 miles.
Ends today, though, and requires an overnight in DEN.