Have you seen the section of this forum called Camping, Campout Reports
? Lots of great info but unfortunately the title
of the threads don't always convey the content. If you use the search option on this forum and use the bottom google option you will get better results.
I enjoyed Buckskin Mountain as well- did you get up to the Desert Bar?
Have done many trips through Oregon and Washington (south west).
Astoria is a great little place to explore so make sure you leave yourself lots of time to check out the old town and the Maritime museum. Fort Stevens State park is a nice park but be warned its a bit of walk to the beach. I have gotten in there a number of times mid week without reservations but reservations are a must if you are going to be there on a week-end.
One of my fav parks in Oregon is Nehalem Bay State Park - beside the little surf town of Manzenta. Only a short climb over the sand dune at Nehalem to the beach. The other is Beach Side State Park - the only state parks in Oregon that I know of you where you camp right at the beach - no big sand dune between you and the beach. Make sure you make reservations at Nehalem if going in the summer as it gets pretty busy. Beach Side is a tough one as well - but last summer I managed to score two spots (one for friends who were following a few hours behind) mid week.
If your staying inland and going through the Portland area Champoeg State park is my fav spot to stay in that area. The sites in the lower loop are newer and bit more space between spots than the older original upper loop. Its a bit south of Portland and about 7 miles off the I5 but worth the short detour off the I5.
In the Newport area its a toss up as there are two state parks to choose from, one North of town (Beverly Beach) and one south (South Beach). Beverly is a little further from town and has more tree canopy. Its a bit of walk to the beach at both parks. South Beach is a bit more open and closer to the town of Newport but due to its openness you can feel pretty close to your neighbours! Have been staying at South Beach of late as I enjoy going into Newport to explore the shops and pick up some fresh seafood from the boats at the dock or to one of the many restaurants. There is also an RV park right at the Marina in Newport that is a good choose if you plan on only spending a night or two and enjoying an evening of dinner and drink. Its in town so you will not need a car.