While you go inland to LA, you can try staying in Burbank. That's where I'm from and it's right over the hills to Hollywood (10min drive through Barham). If you're going through Santamonica/venice, stay in santa monica. Venice can be a little sketchy in some parts.
On you trip down from pismo I would try and cut slightly inland to go to Solvang and Hearst castle if you have the time and flexibility.
For the Peterson museum, try and see if they are doing a cars and coffee weekend. They are definitely worth going to.