Dave, can't help out too much as far as Seatlle goes. But I'm originally from Vancouver B.C.
Vancouver has a lot to offer as far as many ethnic types of food. There are two China towns, the old one in the city, as well as the newer one known as "Hongcouver" which is in the first southern suberb of Richmond= Vanc. Intl'l airport area.
Vancouver has great Chinese for sure, and many different types of Chinese also, Szechuan, Cantonese, Hunan etc. The dim sum is hard to beat for sure as Papa Jack said.
Vacouver also has a great Greek area, Korean area, little Italy, Indian part of town if you're into Curry, Mexican area, you name it, Vancouver has it for restaurants. ALL FOR THE EXCEPTION OF BBQ AS FAR AS I KNOW. I HAVEN'T HEARD OF ANYWHERE FROM MY FAMILY.
My recommendation for Vancouver is if you get your fill of seafood or salmon in Seattle, then try out the different types of ethnic food in the different parts of the city. You may not find another city with so much variety anywhere in your travels. And if you haven't had your fill of seafood, Vancouver has that as well. Salmon just about anyway you like it. Make sure you try some Sockeye smoked salmon, in my opinion the best species of salmon for smoking!!!
Take care, I've really enjoyed going to your website from time to time since I've been a member. Thanks for taking the time to do that!!!!
Best regards, Steve in Taiwan.