I know how hard it is at work, but when we try to get a group meeting together with a large group someone will be left out, and we have a very large group here.
When you guys do get some possible dates that look good to you, you might consider polling the whole group just to see how it works out. Perhaps not. If you look at the Corvette Forum Cruise In II, they got about 2% of their membership to attend their last event. If we did that well, we would have about 20 to say 30 attendees, given the membership will grow.
Ironically they switched to a date for next year which is not as preferential as the old date, according to a membership poll.
Whatever you do, chose your date wisely, and be realistic as to how many will attend.