Hello! I grew up in Torrance and Redondo Beach CA, and family lives in the San Diego area.
Couple of questions to ask yourself before making any decisions. First, do you want to stay super high quality (ie. big money) for all of the places or do you want to mix it up or only stay for moderate or inexpensive? Second, do you want to have one location that you stay in for most of the time and then a day here and there for something else?
My absolute favorite beach is Corona del Mar. It's a little known beach just south of Newport. There is a nice bathrooms/shower area, lifeguards, little snack stand, nice clean beach area with a good stretch of beach. What I really like the most about it, though, is that there's a break-wall right there that (a) keeps the water a bit warmer and (b) keeps the waves a bit smaller and (c) keeps the seaweed content down. There's a public parking lot.
Staying in the Costa Mesa/Newport area might be a good "home base". You can get to DL area in about 15-20 minutes. I *think* you can even get Hollywood bus tours from that area, if not, drive in closer to anaheim and you can.
Unfortunately, there's not really any place near Hollywood to stay that's nice and safe unless you're actually IN Hollywood. If you want a "splurge" night, I'd recommend the Roosevelt hotel in Hollywood. It has a nice little pool area, very historic, right on Hollywood Blvd. And, on the second floor is a pictoral history of Hollywood. Very cool. If you're driving in the Hollywood area, in addition to the "typical" hollywood ventures, I have to recommend taking a walk down Melrose and going to the farmer's market.
Down in San Diego, I really like Oceanside beach. It has a really nice pier and shops and the strand. Places I'd really want to see include the Zoo, the Wild Animal Park, Old Towne, and Sea World. I REALLY enjoy Sea World myself. Skip the LA Zoo.
Since you have older kids, if they are ride junkies, I'd say that a trip to Six Flags is a must.
Sample itinerary.....get to LA, drive up to Six Flags area and stay in inexpensive area there. Last time I was there, they had places like Americinn and Comfort Inn type places out at the exit for Six Flags. Day 2, go to Six Flags. If you're thinking you'd be very tired, stay at six flags again for day 2, if not, drive into Hollywood and spend night in hotel there. Day 3 play around in Hollywood. If you didn't stay overnight, stay overnight on day 3, otherwise, after you've seen Hollywood, head down to Newport. Stay at Newport days 4-8 go to the beach, see area attractions and do DL (or stay in Anaheim near DL and take a day or so to see the beach and other areas). Day 8-10 go down and do San Diego stuff and head back to the airport. These recommendations are for flow of traffic and what I think you might enjoy given the ages in your family.