Your kids would be the perfect age for this tour. We went in Jan '06 and DD5 loved it! She was just learning to read, but the bigger kids got to take turns reading the clues during the scavenger hunt. DH and I also had a blast!
DS3 hated it. He didn't get the story and couldn't stand walking right past all the rides (even though we did the tour on our 5th vac day.) Another 2-3 yr old on our tour hated it as well. We also had two teenagers (maybe 15) on our tour who were good sports coming along with little brother, but you could tell they'd rather be doing something else. They were embarrassed by the silly games and the scavenger hunt was definitely below their level. I'm pretty sure ALL the adults and the kids ages 4-12 loved this tour!
Our Peter Pan was AMAZING! He was totally hilarious. He talked nonstop the entire time he was with our group including the entire showing of Mickey's Philharmagic. Poor Wendy could hardly get a word in!