Santa Monica Pier..Griffith Park..LA zoo
Universal Studios would be fun for them if want to spend day at theme park.
Little further south of LA, Long Beach has a nice aquarium
Orange County has Disneyland & Knotts Berry Farm but doesn’t sound like you have too much time
Also depends on where you’re staying, traffic is horrible.
Good list, I would add the La Brea tarpits / museum. Unique area especially if the kids are interested in dinosaurs. It is in Los Angeles.