Chrisann--
I just wanted to add a couple of things to the information that has already been presented.
1. Disney's Family Magic Tour is one of the very best experiences offered at the Walt Disney World Resort. It is a very special time in the Magic Kingdom, and one that is sure to leave a lasting impression. Almost all guests who take part count it as one of their favorite Disney memories.
2. As has been mentioned, there is a character element to the tour. Very often the character at the end of the tour is Peter Pan. However it is not always Peter Pan. Additionally, as mentioned in a previous message, Magic Kingdom Tours and the tour guide will not be able to guarentee the specific character (even the morning of the tour). As with all character appearances, due to various operational constraints, entertainment is subject to change without notice.
I am confident that you are your son will enjoy Disney's Family Magic regardless of the character at the end of the tour. Additionally, the odds are in your favor that Peter Pan will be at the end of the tour. Currently, it is very rare for an alternate character to be used. Even so... no promises.
Another option you may be interested in considering is a specialty Peter Pan cruise. Keep in mind this Fireworks cruise is only available to grand gatherings (parties of 8 or more staying at a Walt Disney World Resort.) You can find out more about this product at disneyworld.com, but the basic outline is as follows: a dessert reception with Captain Hook and Mr. Smee. A Cruise onto the Seven Seas Lagoon hosted by Patches the Pirate who sings songs, and tells stories. A special viewing of Wishes: A Magical Gathering of Disney Dreams, and finally a private meet-and-greet with Peter Pan back on shore.
Regardless of your choice, I hope you have a magical Walt Disney World vacation. If you have other questions regarding Disney's Family Magic Tour or other Peter Pan themed experiences, don't hesitate to post or send me a PM (Private Message).