For one of my daughter's parties (age 4 or 5) I blew up an insane number of balloons, threw the balloons in a room with the kids, and let them play while the adults talked in the next room. We poked our heads in every once in awhile or when we heard screaming. Everybody had a great time.

For our last party we had unexpectedly good weather so we ditched all our games and opened the door and let them play in the backyard while the adults talked on the deck. A good time was had by all.