Our local quilt shop organizes one in the Catskill Mountains of upstate New York, and I've seen some advertised in the Berkshires and Vermont - a bit more northerly than you want. Quilt Odyssey, a really great show in Hershey, Pa, used to sponsor a retreat, but I don't see any info on their website.
I would ask at your local quilt shop, and maybe think about what MTS is suggesting, too.
Janet