How about a few central/specific retreats? Midwest is just too far for me (all the way in Washington), but I'd be willing to do one in Oregon or even California, maybe. I we did a few, at various times, that we were all invited to (of course), but spread them out all over the country, wouldn't that be easier? Then anyone can attend, but it'll be closer for some, and we'll all have more chances to meet!