I have heard of and witnessed an interesting variety of optional schedules, but one of my favorites is using recreation as an arrival activity instead of a rotation.
With this schedule the front lawn becomes the rec field and the fun begins 30 minutes before the official start time.
Divide the rec field to allow for kids of different ages to play at the same time without the older kids running over the little ones. Choose games that allow kids of all ages to enter into the activity as they arrive.
Be prepared for the number of kids to increase each evening as word spreads that recreation is an early arrival activity.
What unique schedule options have you used for your Bible schools?