In reply to KS132:
June in the Pacific North West is lovely, but it is also one of the wettest months of the year. If you have the choice of being here (I live east of Vancouver) in September you should find that to be a much more reliable month weather-wise for rock climbing. Are you planning to do as much hiking as climbing? If so, your options from May through the summer are vast. May is also nice, but there is often plenty of snow still remaining in the mountains.
I don't think school holidays will be an issue. Folks with kids don't get to climbing and hiking areas that much.
Where in Oregon are you thinking of going? There may be other good places to go but all I know of there is Smith Rock. Which contains a lot of hard sport climbing.
In Washington there is good climbing in several parts both east (dry) and west (wet) of the Cascades. That is where you will find some excellent hikes.
Squamish is great, but usually is damp until July. I think the best time is mid-August to mid-September. Often it has good weather, not too hot and few bugs.
Hope that helps you.