When we head down the coast we like to park at Ft. Stevens State Park in Warrenton Or. You can reserve on line here
http://www.oregonstateparks.org/park_179.php You can use this as a base to wander around the local area to see Long Beach Wa. and Lewis and Clark exhibits. We do day trips out of here to drive south to Tillamook without our trailer so we can see all the beach area an do not have the hassle of finding parking spots long enough. You could hold off going all the way to Tillamook as they have a large parking area at the Tillamook Cheese factory.
A little farther south we stay at Beverly Beach State Park which is just north of Newport Or. While you are in Newport be sure and check out Nye Beach which has some nice art work and local seafood places.
http://www.oregonstateparks.org/park_227.php
The only other place we stayed at lately is in Coos Bay at the Lucky Logger RV Park. This park was OK but we stayed only 1 night if I remember correctly. We had tried to get into Sunset State park in Coos Bay but that was a mistake as it is a tightly layed out park an we had a lot of problems just driving though looking for a spot to park. I had to get of the truck 2 times to have campers move their cars on the corners so I could get through. It is very tight.
When we go to Grant Pass we say at Valley of the Rouge State Park. This park is just off I-5 south of Grants Pass and also works great for a base. We do day trips to the Crater Lake and Medford area from here. It is a nice park that is easy on and off I-5 and I believe they have nature programs here which are fun to take in.
http://www.oregonstateparks.org/park_109.php
When traveling though western Washington be sure and make the trip up to Mt. Baker and drive to the end of the road at Artist Point.
http://byways.org/explore/byways/2236/places/40610
I work camped at Pioneer Trails Campground in Anacortes for a little over a year and we love that area. Be sure to take a day trip on the ferry to Friday Harbor which is quite cheap at around $12.45 round trip.
If you would like some more ideas for Washington you could send me a message.