A great place to spend the day with your family. Our kids loved the penguin exhibit and the prehistoric area. It's quite a bit of walking (as zoos normally are), so bring a stroller or wagon for younger kids. You're also allowed to bring your own food, so pack snacks and drinks.
The butterfly exhibit was closed during our last visit, but the gorillas were out and very active.
If you're staying downtown, getting to the zoo on the train is easy and convenient. Parking is expensive, so the train is the way to go.