L.I.
I don't know if there is one near you or not (there probably is), but we did my 5 year old daughter's part at Pump it up and all the kids had a blast. At 4 years old they could do either Pump it up Jr or Pump it up I think - If you have both near you I would check both out and see what you think or base it on how old the other kids coming are too. Also, for a really great cake that you can custom design however you want that tastes really great too, and is a small fraction of the cost you would pay at a bakery check out http://icedartistry.blogspot.com/ - we got my daughter's Cinderella cake from her and it was the hit of the party. Looked awesome, tasted awesome!