Sorry if repeating others, but here are the highlights from a trip we did a couple of years ago, working from SF down the coast:
San Francisco - Ferry Building for great food, Exploratorium, ride a cable car
Santa Cruz - beach boardwalk, Henry Cowell redwoods and the Roaring Camp Railroad, crazy Bigfoot museum, visit the amazing university campus, Seymour Marine Discovery Center, Natural Bridges beach, walk West Cliff drive and watch the surfers at Pleasure Point, tiny surfing museum in lighthouse
Monterey - Monterey Bay Aquarium and whale watching trip
Big Sur - Pfeiffer Beach
Elephant seals at piedras blancas
We didn't do Hearst Castle this time as our kids are younger (were then 8 and 5) and it was too much to pack in, and I have been before.
Cayucos - tiny CA beach town, we stopped overnight here, sweet little beach town and highlight was cookies from the Brown Butter Cookie Co.
Santa Barbara
LA - Griffith Park observatory, Santa Monica, the Getty Center, Grove shopping mall and farmer's market, La Brea tarpits, Space Shuttle Endeavour. Stayed at a great hotel called The Farmer's daughter which is walking distance to a lot of things so cuts down on the misery of driving in LA (takes HOURS to get just a short distance!) As you have teens you should definitely do Universal Studios in Hollywood, I remember being blown away by it when I was about 16. Our kids were too small when we went.
Disneyland!!
San Diego - we didn't do any of the touristy stuff like Sea World but just liked hanging out in the bay and visiting La Jolla (harbor seals) and Coronado where the Some Like it Hot hotel is.
We did it all in 2 1/2 weeks which was busy but doable. Best holiday EVER - we still all talk about it 2 years later and are desperate to do it all again!