Considering you haven't been to Sea World San Diego yet, you should go, it is a fantastic place. Also, don't go there for only half the day, you WILL spend all day there, and you will certainly want to make the most of it, since they charge quite a bit for admission.
There are various bird exhibits around the park, two aquariums, a third they call an aquarium but it's just a few octopus tanks. The shows are also absolutely fantastic, and they are where you will find the pilot whale and common dolphin (even if it is a hybrid).
There is also a building just for sea turtles, and another for sharks, and as of my visit in 2015 there was a lemon shark in the shark tank.
Should the pygmy sperm whale go on exhibit you will certainly want to go there without a doubt in your head on whether or not you should go. They have a fantastic penguin exhibit, as mentioned, and a very nice arctic area with belugas, walrus, and polar bears.
I would recommend sea world one day and San Diego Zoo another, because if you get to the zoo when it opens at 9:00, you can see it all by when it closes at 9:00. But go to Sea World, and enjoy it, don't take someones word on it from 20 years ago, it has changed quite a bit since then, and I don't see how you wouldn't have a good time (unless you are me who went the one day it rained several inches in California, but hey, I still had a good time).