I have been working with about a dozen other parents informally and have one set of gatherings planned for a certain group.
I realize getting another dozen or so parents to help coordinate (greet and help a gathering along even with a 10 minute circle time and encouragement to pair up with one or two others and learn some names and enjoy the outdoors or whatever event may work) would be one 'next step'.
The bigger concerts at Fort Greene Park in Brooklyn on Wednesday mornings at 10 am (see their site for details ) are nice for people to enjoy with a blanket and snacks with friends...and