S.G.
I operated a play group when my children were younger. We had very few rules. I kept a list of those moms who were a part of it and their contact information. We met once a month, although you could meet more often. We would meet in the park during the summer, or at someones home. We met at McDonalds a few times. At each play time, a mom would volunteer to host it the next time. She would choose a place and make sure that all moms had directions. If we met at her home she provided snacks for the kids and each mom would bring soemthing to share for luch with the other moms. If we met at a park, each mom would pack a picnic lunch for her and her children. When we met at McDonalds each mom purchased for herself and her kids.
It was something that me and my children both looked forward to. When the weather was bad, it was up to the hosting mother to cancel the event. This only had to be done a few times.