Interesting question, since UA splits its SFO-YVR departures between T3 and International Terminal. Since I am 1P (Premier Executive), I discovered that I am entitled to the AC Lounge in Vancouver (StarAlliance Partner) and can bring my ski buddy in for a mere $20. Every international ticket should allow UA ticketholder use of same day international lounge, but Canada is in the gray area as far as "international" is defined from what I read here.