Nehalem Bay State Park boasts 5 undeveloped and uninterrupted miles of sandy beach. Even when the adjacent campgrounds are full, you may just have a stretch of personal space the size of a football field. Just book your stay well in advance--as camping and lodgings are slimmer pickings than the very popular Cannon Beach 15 miles north. At night, the only illumination is moon shine. So here's an after dark tip: bring a light up frisbee, some headlamps and a flashing collar for the dog. You'll feel like you're in the movie Tron.
The beach is adjacent to the small town of Manzanita. If your supplies run low, Manzanita Grocery & Deli have all the basics.