Do not go on Highway 1. It's narrow and curvey. We did it years ago in a Minnie Winnie, what a crazy road and well traveled. It would be a gas in a little sports car though.
We have been doing that trip down the Oregon coast for 35 years. Every year! Even longer for me, been going there since I was a kid.
101 in the Hebo area, that is south of Tillamook, you might be asking...."Are you sure we are still on 101!" it feels and looks like a little secondary road winding through the dairy farms and small towns.
There are some pretty steep grades here and there as well. The Sea Lion Cave area. Also after you leave Manzanita heading north.
It is such a fantastic drive and there are many many, I say many, turn outs and overlooks.
This time of year it is extremely doubtful you will be able to get into any State parks, the majority of them are on the reservation system and booked solid. There are a few non reservation ones, as soon as you get into Oregon, try to find a State Park brochure. (oh duh, just look it up on the internent) LOL
There is a great tourist information place at Battle Rock Wayside. Oh there is a non reservaton State Park at Cape Blanco in southern Oregon, it is breathtaking there. And further up Washburn State park, right on 101 not far north of The Sea Lion caves, it's non reservation as well.
I love the rocky southern coast, from Brookings to Port Orford is just spectacular. From about Bandon on up to Florence is mostly sand dunes. Then from Yachats (my all time favorite spot) on up to Depoe Bay (the worlds smallest harbor) and that is where they filmed the scene in On Flew Over The Cuckoo's Nest when McMurphy takes them all out deep sea fishing. Ok where was I. Not too long after Depoe Bay you'll head inland a bit and come to Tillamook, a dairy farming community with a cheese factory that seems to be a big hot spot for tourists. Also Tillamook boasts a really great airplane museum in an old WWII blimp hanger. It's HUGE.
After you leave Tillamook, when you go through the Wheeler area, the road is really choppy, you know bumps ahead, some places the road is sinking...it is a wild ride if you go to fast.
It's so busy in the Summer along the Oregon coast, but there are quite a few RV parks along with the State and County parks. Florence has a really great county park, Harbor Vista Park, it is really a gem.
Enjoy yourselves, I want to go too! We just spent 2 weeks at the end of May down there.