Is this a group of adults and kids or just adults or solo?
Sea World has a lot of shows, so you have to time out what you want to see and when the shows are (if you want to see them). The zoo also has a couple little feeding times and small educational shows.
I would think you would want pretty much a full day at each. We are two adults and we have gone at opening (9am at the time) and stayed till around 3 or 4. But we linger at the stuff we enjoy- but also walk quickly through the parks. With kids I would think you would want more breaks for snacks and lunch/potty stops/ and to go a little slower.
We love the zoo and we LOVE Balboa park- make sure you work in a at least a quick stroll through the grounds there or the botanical gardens. So pretty! Have fun!