David,
I go there a lot I guess. For the mammals your 70-200 is what I used last time, although it gets pretty heavy after an hour or two. A macro of some type is pretty handy as well for the fish.
One mistake I made at first was to try and get only photographs of the animals and fish. I now believe the best photography is taking photographs of the people interacting with the animals.
I don't know whose kid this is, but thanks for letting me borrow him for 1/20 sec.
Just a thought. Anyway, I hope you and your family have a lot of fun (go early, 10 am).