+1 for what Matt said.
I've worked with groups as large as 25 to 30 climbers and 5-6 leaders at St. John's. (Including Matt.... ;-) )
Lower ledges gives a handful of easy short lead routes with excellent access, a clear base area that can support a large number of people, with no damage to vegetation, and no poison ivy to boot.
The Upper ledges are an honest 80-100' in places, with a few of crack/corner climbs that can take gear, and excellent slab climbing that will take the occasional piece for bolder climbers. These are perhaps better suited for TR. Also has lots of room for groups to spread out with minimal impact.
Tons of local camping, easy access to amenities, no parking issues, a "woods" setting, ( no paved roads or houses anywhere nearby), and very short approach.