There are cheap V class fares available from Australia for that period so I would rather go transpac on UA.
Having said that, the direct AC service SYD-YVR is going to be a real winner for Australia/Canada travel - in the past,having to transit US at HNL both ways made many of my friends and colleagues think twice about skiing up there.I know only too well the customs immmigration hassles US/Canada and vv as we go skiing each year to BC or Alberta and I still remember last year's queues and the arrogance and rudeness of the US officials at YYZ.
The LGA- YYZ option looks good to me - I'll check on the dates.
Thanks for all your input .
Ozflier