Getting a Zoo Pass Plus is one of the better family entertainment values I have found. (The "Plus" is the parking, without the "Plus" parking is $7/each time although there is ample street parking in the area) If your children are younger, you will love having the freedom to drop in for an hour or two and when fatigue starts to show (as it will, so many places to walk, so much to see) you feel no remorse over leaving to return another day.
I know a fair few families (ours included) who stop in nearly every week during warmer weather -- and never tire of the experience. There are so many animals to see, special exhibits, shows, the zoo train - naturally, and frequent special programming. Our favorite is night light at the zoo each December, but we also enjoy the behind the scenes weekends (there happens to be one right now) when you talk to zoo keepers and learn so much more about the animals and their care. And Zoo Classes are a huge hit with all of the kids we know (classes are divided by age, so activities are appropriate for your child from 2 up.) Ample picnic spots mean you can bring your own lunch or take advantage of one of the zoo's many restaurants.
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