Birthday location help: Chicagoland

[FallBabies]

I live in the NW suburbs, all the family is in the far south suburbs. DS will be turning 1 in May, and I need to figure out where to throw his party. Suggestions?

If I do it up here, we will invite friends, so lots of kids will be involved (15-20.)
If I do it toward family, it'll just be a max of under 10 kids.

We can't do outdoors due to weather at that time of year, so I'm trying to figure out a good indoor place that isn't overly expensive. My budget is open at this point, but the cheaper the better.

TIA!