B.V.
I would try some of the Rec. centers. I know the one on General booth is NICE!!! GREAT room for many people! And they provide a cake and balloons and plates. but you can bring what ever you want too! It's a GREAT place!
Also try some parks if you're looking for a HUGE family outing. Mt trashmore or even Munden point park off of princess anne. Need to book soon though!