We drive the Oregon Coast about every two years. We really like it up there. We always make sure we hot the coast in August and beyond.
Do the whole Oregon Coast. Golds Beach is a nice stop with several RV parks in the area. The big attraction there is Jerry's Jet Boat rides. It takes you up the Rogue River in a large 50 seat jet boat. It ahs both a lunch and dinner run. The dinner run is the best.
The Mill Casino in Coos Bay is a nice RV park with a Casino attached. There are several things in the area to see. Make sure you visit Cape Arago State and Shore Acres State Park. There is a beautiful bay there, a great turn out farther up the road where 1000's of sea lions spend the summer and some beautiful gardens run by the County. There is also a small main street with some antique shops and some pretty good seafood throughout the town.
As you enter Oregon from the south, one of the major towns on I-5 is Grants Pass. You can tube the Rogue River there. A few miles north of Grants Pass is one of the nicest RV parks in the U.S., called Seven Feathers. It has fuel and a casino.
Probably the nicest park in Oregon is the one mentioned above at Winchester Bay. Just beautiful sites atop rolling hills of grass. Make sure you stop there for a few days.