I've seen Cirque for free and I've paid for it both in Vegas and Orlando. It is a "must-see" for anyone.
Knowing that, I can tell you that I would not bring my kids, almost 7, 5, and 3, to see Cirque yet in Vegas or Orlando. They absolutely wouldn't appreciate it to it's fullest, and I would never want to interfere with someone else's enjoyment of an adult entertainment product.
JMO...Patti