For my return flight(s), my Air Canada app offered me seat selection for each leg of the journey, with diagrams of what seats were available - hardly any, considering this was at the earliest possible check-in time. So, I carefully made changes to my assigned seats for each leg of the journey, hit <Save> and got their message that "Unfortunately, seat selection is not available for this flight." Fortunately, I was assigned an aisle seat for the YVR-BNE leg. I must say it's great on such a long flight to be able to just stand up frequently and have a stretch and move the feet around. Apart from having to stand up to let other passengers out, the only downside was that one of the hostesses was somewhat generously proportioned (not that there's anything wrong with that) and her hip would bump into my shoulder every time she walked past. They need wider aisles or narrower hosties. Now I'm back, with access to a laptop, I can see that option (not available on the mobile site). Would recommend it in the strongest terms for anyone wishing to fly to Sun Peaks from Oz with Air Canada in the future.