I love our zoo here in Memphis. It's very well-designed and growing - a new exhibit just opened, another big one is planned to open next year and they're building a giant nature hiking trail.
We're season pass holders; you only have to go twice to make your money back. I had the day off yesterday, so I drug the kids out to give J-mom some time to do schoolwork, etc.
One of the things I dig about the zoo, is that you never know what the animals are going to be doing. For example, I didn't think the elephants were going to be so affectionate:
We went through our nocturnal exhibit and, I don't know what this is, but he was either not fooled by the artificial darkness or was dead:
Bring a bag lunch, some bottled water and it's a great way to spend a few hours.