You can indeed access Priority Pass lounges with your Amex Plat card. I did this at YVR yesterday, and YYZ last Wednesday (both domestic, but I understand it's the same policy for all their lounges now).
The main PP YVR domestic lounge is a few minutes away from the cafe style one. Although they claim the f&b offerings are the same at both, I prefer heading up to the main location (even if I'm flying AC and have a longer schlep to the gate). They have a very nice pale ale from Bomber brewery on tap (and some other craft lager, IIRC). Food was pretty decent, too.