With three days on the Oregon Coast, I would suggest spending a good portion of your first day between Brookings and Gold Beach. The Samuel H. Boardman State Scenic Corridor extends about 12 miles north from Brookings and includes several easy stops with rewarding views. My favorites are Whaleshead Beach, Natural Bridges and the Arch Rock Viewpoint, though if you want a great short hike, the short walk to Thunder Rock Cove is a great one and can be extended to Secret Beach at Miner’s Creek.
A great second day would include a drive north to Port Orford where Battle Rock Park is a nice highway side-stop and Port Orford Heads State Park offers great views along some short trails. You can continue north for a quick side trip to the Cape Blanco Lighthouse in a beautiful setting. I would spend my second night in Bandon where you should save time to enjoy the beautiful beach and its remarkable rock formations. Walking this beach is spectacular and viewpoints, including Face Rock and Coquille Point, are stunning.
I would suggest going as far north as Cape Arago by following the Bandon to Charleston Tour Route. There are three Oregon State Parks on Cape Arago that offer some of the best views and experiences on the Oregon Coast. Shore Acres State Park is one of my favorites, especially when the surf is up. The nearby Simpson Reef overlook is one of the best places to see seals and sea lions in their natural habitat.