Starting south from SF (and there are too many things to list for SF itself, but search previous threads), you can hit:
http://beachboardwalk.com/ Santa Cruz beach boardwalk would be a big hit with teenagers
Monterey/Carmel/Pebble Beach, including
17 Mile Drive,
Monterey Bay Aquarium, Cannery Row, Pacific Grove, Asilomar, etc, etc.
Just south of Carmel,
Point Lobos state park is a real gem -- beautiful views, great hiking.
About 20 miles south of there is where the Big Sur coast really begins. Mostly, you'll want to ooh and aah at the scenery, and stop at a lot of turnouts. But for lunch/dinner, I can recommend
Nepenthe's. Definitely pricey, but worth it for the views alone. For a less pricey meal, you can get take-out at the general store in the town of Big Sur, or for something in between, a sit-down lunch at Big Sur Inn.
Lots of places to see along the Big Sur coast. Then, just as the coast scenery is winding down, you'll run into
Hearst Castle. It's an amazing site, but if you want to see it, you'll have to book tickets in advance. Preferably at least a couple of weeks in advance. And if you're short on time, know that it will take several hours.
South of there, you'll run into San Luis Obispo and Pismo Beach, Solvang (cute little Swedish tourist town), Santa Barbara, and Ventura. After that, PCH (Pacific Coast Highway) starts. Note that north of there is NOT called PCH, it's Highway 1 (officially Cabrillo Highway). PCH is beautiful through Malibu, though not nearly as breathtaking as Highway 1 through Big Sur. After Malibu, you get into LA.
Hope that helps,
Bob