I've had similar experiences, one specifically at Wicked a couple of years ago. I don't really consider Wicked to be a "kids show", so I would think that if your kids wanted to see it, you best make sure that they are old enough and mature enough to sit through the show in a theatre full of adults!
I had two kids sitting behind me (with their parents off in different rows - smart thinking) who made such comments right off the bat, like, "Ohhh look, there's GLINDA!" (Said at top of lungs) and "Wow, she's so pretty!" and proceeding to sing every one of her lines. Needless to say, that didn't last too long...I turned around and 1. told them (in no uncertain terms) to be quiet and 2. to ask where their parents were to quiet them down.
At the end, one of the kids said, "Wow, Glinda is just so good, and that Elphaba is just so bad."
Clearly the whole point of the show was missed entirely. Are these kids really old enough to be seeing this show, when they clearly weren't old enough to understand the "moral of the story?"
End rant.
"You see, I told you so! There's lots of things I know. 'Ponine, she knows her way around."