My DDs (9 & 7) have been to both Simba's and Neverland Club at the Poly and they love them both. Simba's seemed to be much more structured and the woman who was in charge was delightful. They were a little nervous at first (we homeschool and they are rarely away from me), but the lady was very light and matter-of-fact and got them going on an activity right away after a "Give mom and dad a hug and a kiss and let's get started!" We were running late one evening (not late past closing, but later than we'd said) and she was so kind, telling us to take our time and reassuring that DDs were fine. When we arrived, they were sacked out on the floor with blankets and pillows watching a movie.
Now, for my DDs, *NOTHING* beats the Neverland Club at the Poly. It is a bigger club, less structured, but with lots more "atmosphere". There is a big game area, lots of crafts, a dinner buffet (served from the crocodile!) as opposed to choosing a meal at Simba's, and movies. All the clubs have lifeguards that come to help out as part of their training, too.
On our upcoming trip, DH isn't going, so DDs were plotting things for me to do alone so they could score an evening at the Neverland Club...that's how much they love it.