Long time BA flyer with piles of Avios, and with changes to Avios redemptions, the SEA-YVR segment isn't included and for family of five it's easier to just drive a one way rental car.

BTW, we flew a crazy northern route and actually came across eastern tip of Mongolia on way to HKG. Business class was funny, my three little kids and then mostly college kids heading home. I certainly didn't get to travel like that as a college student!