I exchanged my Canadian bills for Korean won on my recent trip to Seoul both in Canada and Korea. For Vancouver, I would recommend Vancouver Bullion and Currency Exchange. They only have a couple of branches though (Richmond, Downtown, Broadway), with 1 supposedly opening up at Metrotown in the Fall. I also went to Myeongdong, since many people have expressed better exchange rates at the money exchangers here, but I brought $50 bills which affected the rate. Jajangmyeon1 above mentioned that they only accept new $100 bills, so keep that in mind!