For San Diego the WildLife park is about 30+ miles from downtown SD so quite a haul. It's great but I think I like the zoo better. I would suggest also just walking around Balboa park. There are some great museums in the park. The air museum is great. The Fleet science center. A nice natural history musesum. Even a really cool miniature train area.
Santa Barbara has a nice little zoo in it's own right. Oh, nothing like SD's zoo but still nice.