From Lincoln City, drive south along US Highway 101 until you pass through the Siletz Bay Wildlife Refuge just beyond the bridge crossing the Siletz River. If you come to the Salishan Resort, you've gone too far. Park in a pull out on 101, or drive the perimeter road on the south edge until you find a decent place to park.
Oregon is known for its rain, so bring along wet-weather gear and waterproof boots such as Bogs. An umbrella is helpful in keeping you and your equipment dry, and microfiber / cotton towels help keep your lenses clear of raindrops. In the spring, there are often blooms of skunk cabbage which can provide great foregrounds for you wide-angle shots, or work well for macro work in the high overcast light. Detail shots are great filler while you wait for clearing storms, or if the day is overcast.
Siletz Bay NWR is along US Highway 101 just south of Lincoln City, Oregon. The area is a coastal wetland which borders the Siletz Bay and the Siletz River. While it is closed to the public, a photographer can hike the perimeter and photograph the canals, marshes, bordering forest, and wildlife. Be cautious not to intrude upon the private properties, though, and make sure to bring along waterproof boots as the ground is quite boggy. The bay gets its best light at sunset as the coastal mountains block the rising sun until late morning, but stormy weather provides what I believe to be the most drama.