
We just got back from the 3/13 Wonder, and my DD is 2 1/2 and not potty trained.
Since my older DD was in the Oceaneer's Club, I would often bring my younger DD with us. We'd hang out for periods of time, and she loved it!
You have to be visitor, but the cast members love it when you are. Your DS will get a visitor sticker, and learn to wash his hands just like the other kids.
We hung out for many of the character appearances, dances, and all the rest.
Also, when she was in Flounders, the wonderful cast member (can't remember her name, from Brazil) even let her go visit her sister so they could be together. So both girls were together in the Club. It was so comforting to know they were out for her best interest.
They had to keep checking on her, but when they weren't busy, they could do that.
We were so relieved, and knew the girls were really happy!