I was trying to book an award ticket through my SE Aeroplan account for a relative. She had to go from YYZ to Grande Prairie - either via YEG or YYC.

For every day last week through to Sat Dec 28, and also today - plenty of priority award economy seating on all days. On Dec 29, most (but not all) flights had zero availability of priority award economy seating. On all days from Mon of last week through to today (including Dec 29), priority economy award seating available on practically on all AC flights between YYZ and YVR.

Taking account everything that has been said about YYZ-Alberta traffic being heavy, and perhaps weekends being especially heavy - for me, the difference in availability on Dec 29 for Alberta bound flights versus YVR bound flights, stood out. Also, there was plenty of availability between YYZ and YWG on Dec 29. I did not check for availability between YYZ and Regina or Saskatoon.