What time of year will this be? It can make a difference.
What are ages of kids?
Some of your driving days seem pretty ambitious. The drive from Santa Clarita to Monterey on the Pacific Coast Highway will be pretty much all day in the car. Some of the finest coastal scenery in the world and little time to stop off occasionally along the way and enjoy it.
Would it be possible to rearrange your flights to arrive at LAX or SAN (San Diego) and depart for home from SFO (San Francisco) or SJC (San Jose)? Eliminating that long backtrack to LA would make for a more relaxed and enjoyable visit.