Not sure why you think you can't do one week with Seattle and Vancouver. Vancouver is not that far of a drive from Seattle. Or just spend the one week in Seattle where there is much to do. I personally wouldn't start rethinking of somewhere to go especially since it's almost mid-July and airfares are so expensive for the rest of the summer. Realize that both Seattle and Vancouver are cruise ship ports so you could always plan on taking a cruise next year and see both cities along with Alaska.