Any tips for putting together this kid's party/get-together at my church?

OK so. I just got this idea (Actually, it’s been kinda stirring around in my head for a while). I want to put together a “Parent’s Night Out” at my church. I’m thinking the parents (there are about 10 or 12 families in the church, it’s a pretty tiny one) could bring their kids to the church and we’ll take care of them while they go on a date. I want to make it be a fun evening for the kids. There are a few rough spots in the plan before I ask the youth pastor about it.

At first I thought the entire teen group could do it, but then I remembered the 7th grade boys. They are SO immature! I don’t think the world would be safe if they got that much power. How exactly could I keep them from being in charge while still having enough people to keep the kids under control?

Also, I don’t know if I want all the kids to deal with at one time. It’s not like I don’t like some of them or anything, it’s just that it’d be hard to deal with them all at once (there are about 30–40 kids in the church, including preschool kids). What would be a good place to split the age groups? Could I have two separate parties, one for the younger half and the other for the older half?

All tips would be hugely appreciated.
Sorry about the long schpiel. Oops :)