I've been OC'ing in Vancouver since December of 2009, whenever I'm at home from college.
So far, I've been asked to leave my firearm outside at only one place, Izzy's Pizza on Mill Plain; waitress asked me if I'm an LEO, and then asked me (very nicely) to please leave it outside, which I complied, and once I came back in, she was just as friendly as ever. Said it was just "their policy" to allow only LEO's to have their sidearms in the restaurant; civilians cant even CC into there. I sent their regional manager an email, and she got back to me saying that they don't have a specific policy on OC/CC, but since the sight of a firearm can make other patrons nervous, she requested that I leave it in the car.
I've carried into various Bi-Marts, Walmart, Old Country Buffet at the Van Plaza (manager asked me about it, and made it clear that he has no problem with it but had to ask so he could give an answer to curious patrons), Petco on 4th Plain, Wholesale Sports on 4th Plain (they do ask that you clear the chamber and leave it unloaded; though there's a not-so-big sign that says you should check your firearm with the front, no one enforces it), Subways, the BOA branch on 192nd, Fred Meyers, Safeway, Target, the Vehicle Emission Testing center on 136th, Papa Murphy's, Barnes & Nobles, and probably a couple other places that I'm forgetting atm.
Hope this helped!
And welcome to Vancouver; glad to see another OC'er here!
PS. I'm also the guy that started the thread "SW Washington (Vancouver) OC report"