Have a great time!!
We love the Bronx Zoo. My kids love the tram ride. They are big elephant fans and it is the only place to see them. Like everyone else said, the tigers and gorillas are must do's. We love the butterfly house and the bug carousel. It is alot of walking. Make sure you are wearing sneakers.
Thanks to all who responded. We had a great time in large part to your advice. We are totally pooped. I am in love with the gorillas. We walked about 5 miles today according to my pedometer. To think we do that for 7+ days when we are at Disney. LOL.