The kid spa, if I remember correctly, is really just a small cove off the busy back 'lobby' area. If you pass through the food court, pass the arcade, pass the gift kiosk, you'll come to a big, open lobby. There is face painting, balloon sculptures, and a large room on either side of the lobby. Then there is a small alcove, not walled off from the lobby, where they do hair braiding, mini-manicures, etc. If I am remembering correctly, that was the Kid Spa.
Someone else may know if there was more to it than that, but that's what I recall.