Depending on how much time you have, I'd consider Sea World, Coronado Island, & Balboa Park before the Safari park.

Also leave some time for the beach. Moonlight Beach in Encinitas is big and family friendly, and you can have a fire if you bring your own wood. Also the beaches in Carlsbad are nice and probably the least crowded. Mission Beach has some nice grassy areas. Further north, there's a pier in Oceanside.