Yes, we've done it several times. There are all kinds of state parks and campground along the coast highway. One of our favorites is Pacific Beach State Park, near the town of Pacific Beach. From there you can drive north up the coast road to the Quinnault Indian Reservation. If you ask at the tribal office you can get a pass to go on the beach there. You'll find miles and miles of unspoiled, uninhabited beach to roam ( just be sure you park well above the tide line)
For more info go here:
http://209.206.175.157/thingstodo.htm
There are also many beautiful campgrounds in Olympic National Park in NW Washington.
In the town of Westport there is a cool little campground called Grizzly Joe's. It's right on the water, and you can rent crab traps and catch your own dinner off the dock. It's also a nice short walk into town for some interesting restaurants.
If you're interested, send me a PM and I'll send you a link to all kinds of pictures from that area. I would have to take a look at the pics myself to remember the names of all of the campgrounds and scenic areas.