On my return, we got to work doing research and have picked a place to try this autumn. It could be the first of a couple of tries or it could turn out to be our permanent retreat site. We'll see.
Meanwhile, the group had agreed that on Friday night of retreat weekend, we'd swap some blocks. The parameters were kona black background, 12" finished, with cool color "read solid" batiks. I chose Double Pinwheel and as of this morning, all nine are finished! The swap will yield me nine different blocks of those specifications. I'm thinking I should make a few more individual blocks, as nine won't add up to a very big quilt.