I have been studying up on this too, so heres maybe a little more beta for ya-
>> Wheels & Water
If you want to salivate badly while still stuck in middle of winter in the Rockies read up on Nate's posts and videos on his blog of OR/WA/CA runs.
he posts videos every now and then on the buzz, which is how i came across his stuff. everthing is documented thoroughly. he does a really good job with stills, headcam vid and info on everyrun. the Ohanepecosh looks ILL!!! and Canyon creek... holy crap. yeah. drooling in the desert.
also the River Gypsies guide to North America is nothing but the classics. and PNW/BC section is right at the beginning. great reading although its much less applicable for me...looking for the awesome III/IV's, not the classic V's. its got directions and descriptions to many of the runs listed above.
I am going to Hood River/Portland area end of June so I am interested to know what moderate stuff might be flowing then, although i know it may be the driest part of the year, thats when I can go. So If anyone has the lowdown on that time frame I'd love to hear about it. thanks!