My 7 yr old DD did the Cooking class for the first time in October and she really had a great time!!!! Again, there were mostly girls in the class (maybe one or two boys). On the day Allison did the class, the age range of the kids seemed to be about 6-9.
All the kids seemed to have had a great time, when we went to pick them up!!
Also, I did have to give my credit card # when making reservations; and when we went to check in, the credit card had already been charged - all I had to do was sign the receipt. (Same thing for the Alice in Wonderland Tea Party)
I would also suggest leaving it up to your son - if he wants to attend, I'm sure everyone will make him feel welcomed. If not, maybe you could do something special with him!
Enjoy!!!