Hi
peyjax! We have three boys (ages 5, 11 and 12) and we just did this a couple weeks ago! As for the timing, we did this in seven nights and eight full days.
We started in San Francisco, and spent two nights there. We took the kids across the Golden Gate bridge, walked around the Embarcadero, Fisherman's Wharf, Ghiradelli Square, Pier 39, etc. We purchased Alcatraz tickets far in advance and took the first boat of our first morning there. We spent some time at Golden Gate Park (outstanding playground!) and they ran around at the beach. We walked quite a bit - from North Beach to Union Square and rode the cable cars down to Fisherman's Wharf.
We drove to Monterey, spent the afternoon at the aquarium (GREAT for kids of varied ages) and stayed overnight there for just one night.
Then we drove down 17-mile drive, stopped in Carmel, and followed PCH down to Santa Barbara. We stopped at a few beaches for the kids to run around, at Julia Pfieffer Park (amazing and beautiful), at the Whale Watcher's cafe for lunch, and at Hearst Castle just to see it from the observation deck. We ended that day in Santa Barbara and stayed overnight there.
The next day, we drove down PCH to Santa Monica and then hopped over to the freeway and arrived in Newport Beach by noon. We spent a few days in Newport (and one of those in DL.) I just started a Newport Beach thread with lots of information and photos that might be helpful:
http://www.disboards.com/showthread.php?t=2895078
We also love Catalina Island with kids, and during our last visit, we also spent a wonderful afternoon with the boys at Crystal Cove, just south of Newport.
Our plan was loosely based on my experiences as a child - we spent lots of time in the Bay area and did the PCH drive a number of times. So it was great to introduce our kids to so many places I had visited long ago. We had a great time and our entire family really enjoyed the trip. I'm happy to provide more details and restaurant and hotel recommendations if that would be helpful. Happy Planning!