Which hotel are you staying at in Santa Barbara?
This is a sample itineary that I would recommend (link opens up Google Maps):
https://www.google.com/maps/dir/Los+...34.5958201!3e0
If you leave on Sunday, I recommend leaving before 10 AM. Traffic is light and you can grab breakfast in either Abbott Kinney section of Venice or in Santa Monica.
Here are the stops:
1. Abbott Kinney Blvd (light breakfast option)
2. Downtown Santa Monica - follow the route, you will end up at the parking garage at the mall on 2nd street. Leave your rental car there (2 hour free parking) and explore Santa Monica and the pier area on foot.
3. Take California Incline to PCH, stop at Getty Villa (advanced reservation required). If you are hungry, there are lunch spots along PCH, both sit down style restaurants and road side shacks. Or try the Getty Cafe.
4. East Cabrillo Blvd - one of the first exit when you get to Santa Barbara (this exit is on your LEFT... very unusual in the US). Take Carillo Blvd to the Sterns Wharf - it is one of the last remaining wharf on west coast that you can drive your car onto. If you haven't eat lunch yet, this is a good spot.
5. Drive down State Street (the main street in Santa Barbara) to Paseo Neuvo shopping center - leave your rental car there and explore on foot. Alternatively, you can head to your hotel.
On Monday morning, you can spend more time in Santa Barbara or you can take a drive up the hills above Santa Barbara toward Solvang (up to this point, your drive is entirely on the coast and flat). You will be in Santa Ynez wine country - visit some vineyards for free tasting if that is your thing.
Solvang is a small town with a fake Danish village downtown. It's a bit of a tourist trap but not cheesy (it's fairly low key and delightful). You can eat lunch here then start your drive back to Los Angeles.