The Canadians really do make it quite easy on you both coming and going. I did a SAN-YVR-PVG-YVR-SAN run and it was very easy. I left a bag of Chinese souvenirs at customs on return and the YVR airport authority returned it to me, in tact, by UPS at my expense of course. The Vancouver Airport is really quite a beauty and is a comfortable place to hang out if one has to.