Thank you!!!

I did a bit of digging online and found that apparently, the most scenic part of the route was the Monterey - Morro bay stretch. Taking into account your experiences, I have slightly changed the route:
Day 1: Fly to San Francisco
Day 2: Golden gate bridge and walk around Pier 39 (like real tourists

)
Day 3: Walk around San Francisco in the morning, drive to Monterey
Day 4: Monterey Bay Aquarium!!!
Day 5: Whale watching and more fun
Day 6: Drive past Big Sur along Route 1 and arrive at Morro Bay. Elephant seals.
Day 7: Drive to Sequoia NP and walk around in the late afternoon
Days 8 and 9: Sequoia NP hiking
Day 10: Morning in Sequoia NP and drive down via Bakersfield to LA
Day 11: LA
Day 12: LA and then drive to San Diego via Route 15 to avoid traffic
Day 13: SDZ!!!!
Day 14: Get back to LA and fly back home!
Sadly since my parents aren't the keenest of zoo visitors, I don't think we can visit more than 2 collections without them losing their sanity. So... I guess LA zoo and SDZSP will have to wait...

. The reason why we have to go from San Francisco to LA at least is because we need to fly there and back, so... Plus, we do need to see San Francisco harbour because my grandparents lived their for 6 months on their boat before their attempt to cross the Pacific on an entirely self-built boat