Oregon:
*Mt. Hood - east of Portland - is really nice if you are into mountains and remoteness.
*Ecola State Park - west of Portland - is really nice if you are into the ocean and rocks.
*Crater Lake National Park - roughly the center of the state - is pretty cool. Some nice hiking around the volcano.
*The entire Columbia River Gorge is really nice (waterfalls, cliffs & mountains, etc.).
Northern to Middle CA:
*In Northern California, go to Redwoods National Park, any of the various units.
*Lassen National Volcanic Park is really awesome, and unlike most national parks is relatively empty of people. It is really pretty, and has a lot of geothermal oddities (hot springs, geysers, etc.)
*Yosemite National Park is probably the most awesome national park of all, but good luck getting a campsite, and prepare to be overrun by the crowds.
*Kings Canyon/Sequoia National Parks (really one big park) is really nice, but suffers somewhat from the crowds. If you want to get away from people, go to the Kings Canyon side.
*The Pinnacles National Monument is a little remote, but incredibly awesome if you are into rocks/rock climbing. Some of the trails (especially the ones through the talus caves) are incredible.
Southern CA:
*Death Valley National Park. This is an awesome place to be, with lots of great hiking and things to see, but its probably way too hot this time of year for comfortable camping.
*Joshua Tree National Park. Another incredible hiking/climbing park, but has a lot of the same summertime issues as Death Valley.
Just ask if you want more detail on any of these suggestions.