101 is very good for big RVs although you won't be traveling fast. There are plenty of pull-offs. There are many bike riders so be alert for them. It's a beautiful drive, especially for north to south where the pull-offs will be on your right and very easy to access. Have a good one!
P.S. You asked about 4-wheeling along 101. We have found it's all about the beaches. No 4-wheeling like you enjoy in Utah/Colorado. :) There are some forest roads but usually all you will see are forests - no wide open spaces. I don't think you'll want to take your vehicle to the sand dunes but perhaps renting a dune buggy would be fun for all. So..do all the 4-wheeling before you hit the beach areas!
