There is so much to see in this area, it can take all day. There is the zoo, aquarium, gift shop, rose garden, Kidz' Zone, and I really like the Humpty Dumpty site. There is a multitude of stuff here, and I cannot remember them all.
In the zoo, I especially liked the naked mole rats. Cheap thrills.
For walking outside of the zoo, there is no charge. How nice is that?