A native Californian and longtime RVer, I agree with those who caution you about traffic. Travel is about time, not distance. I live in Anaheim (think Disneyland) about 28 miles from downtown LA. That trip can take up tp two hours at certaintimes of the day. Check out Dockweiler RV park in Playa del Rey. On the beach, near LAX. Good location for daytrips to LA-based attractions. Orangeland RV in the city of Orange is a great place for Disneyland, Knott's Berry Farm and the beaches. Bolsa Chica State Beach is on the beach with full hookups but tough to get reservations. Keep in mind that there are more than 10 million people in the five-county LA Basin so RV spaces are in high demand most of the time. In the San Diego area, check the Chula Vista KOA. Great location for the zoo, Sea World, USS Midway, etc. Enjoy your visit.
I agree with those who say that if OP doesn't reserve ahead for the weekend, tough luck. That said, I avoid Reserve America like the plague. They're overpriced, their people are rude and poorly trained and they have no clue about the business they're in. We've had so many screwups in RA reservations (one ranger in Colorado got us a refund when we showed up in our 36-foot 5th wheel because RA had saved us a space for a popup tent trailer) we've just given up on them. And they do make a racket out of reservation fees -- limiting the length of a reservation but letting you make two back-to-back reservations and charging an extra fee. Of course, since states have been hiking their rates to make up for lost revenue during the recession we've stopped staying in state parks and use more private CGs. Not as scenic but often cleaner and their people seem to actually want you there.
We've visited Oregon in RVs for over 40 years, finding new and special parks on every visit. Here are some of our favorites:
- Columbia River RV in Portland, just off I-5, easy in and out, clean and well-maintained, all concrete pull-thrus, close to the light rail into the city for tourism.
- Cascade Locks KOA (others have already mentioned this one)
- Seven Feathers in Canyonville (ditto on others)
- Deerwood RV in Eugene, big rig friendly, close to U of O, Monaco plant, outstanding Oregon wineries like King Estate
- La Pine State Park south of Bend, full 50-amp hookups right on the Deschutes River ... Lava Lands National Park volcanic area all around
- Leisure Time Resort in Seaside on the coast, a Thousand Trails/Encore park that also accepts other memberships/affiliations
There are literally hundreds of great places to stay in Oregon and thousands of places to see. We haven't run out of new discoveries in 40 years. Happy travels!