If you want swank, go to Cannon Beach. If you want campy, go to Seaside. If you want to play on the beach,
I'd go to Oceanside. Not a lot of people there, no shopping quiet town, great beach. 10 minutes from the Tillamook cheese factory.
Be sure to rent a boat and go crabbing. If you are there in August, get a guide to take you salmon fishing at Buoy 10.