Your kids are the perfect age for this. It is very neat!!! I would definitely recommend it if you have the time in your schedule. However if you are going in July thru Sept it gets HOT out there (prob 15-20 degrees hotter than Anaheim).
It's a long trip from Anaheim though, close to 2 hours. Not sure about a tour bus. We always get there at opening, it's much cooler and the animals are more active. Might be easier and more flexible to rent a car for the day. Good luck!