I went to Vancouver last June. You can PM me if this information isn't sufficient enough...
Definitely go to Victoria, on Van. Island, for Skylark--they're quite easy in June.
If you're interested in pelagics, good luck, but the best we could find (Note this was a family vacation, not a birding trip) We actually took a whale watching boat off of the west coast of Van. Island, Tofino, I think.
If you have time, I believe they're called the Charlotte Islands or something, which are a long ways from Vancouver, but hold a wealth of nesting seabirds.
Manning Provincial Park is excellent for Boreal species, and the Vasuex Lake area is excellent for birds impossible to find in other parts of Canada. It is very arid, and has such cool species as White-headed Woodpecker, etc.