This seems obvious, but the location is a very important safety factor. Parents will feel nervous if it is too far away from the church. It asks for trouble if it is too close to the parking lot. Also, having the playground out of clear lines of sight is not a good idea.
Choosing a location that the parents are comfortable with is important. There may be some louder voices saying this location is better than another, but you need to filter them out to hear what the parents are concerned about. Their children will be using the swing set, and if mom and dad do not feel at peace, then the playground may sit empty.