This is what I did, I live in the southwest suburbs of Chicago, so familuar with the area, the cook county has forest perserves rhat you can rent out, and will be reserved for you. Most have pavillions, picnic tables, check on the internet for information- Cook or Lake County Forest Perserve Districts- I was in the Palos area, cook county, set up volleyball, there were small lakes for fishing, hiking trails, outsdie fresh air, plenty of room, Or pending on age groups could try one of a few idea's, A " PGA " place, has arcade games, etc, where you play, and get coupons, at the end,turn them in for prizes. Most have a seating area, and have food & soda, Also, In Milwaukee, they have great festivals all summer right on the lake They have german fest,irish,polish, american-indain, french fests, each has it's own ethic food,entertainment stages, drinks, it's on a huge ground,so staying together could be a problem. Also, maybe a VFW hall,some have large halls, with grounds on them for outside activities,have fun