My mom lives in Indiana about halfway between Illinios and Michigan, twenty or so minutes from 80, 90, 94, and the Indiana Dunes State Park. She's got a couple acres complete with pool and horseshoe court, and is very hospitable. (Ask Bill and Allan, she entertained them on their trip until I got there from work.) I could check, but I'm sure she'd be willing to let a bunch of us gather there for a day/weekend. Not only willing, but probably enthusiastic about it.

Having grown up in that general area, I could name a few places that we could gather if anyone would prefer a public setting.

My only constraint is that I'll be out of town from 6/22 thru 7/13.