I'm in North East Pa, (NEPA). I have Knoebels Amusement Park available to me. Something like this is another thing that you can look at.
In this Park you can reserve a pavilion, it's free of charge for this. The admission to the park is also free, you just pay for the rides, and that price is reasonable also.
Knoebel's also has a camping ground, trailer ground, and they also rent cabins.
The pavilion is equipped with a BBQ, or you can bring your own. If you rent a pavilion, you can actually tell them at parking, (which there is charge for), and you can park at that pavilion. Providing, that it isn't that big of a "retreat". I'm sure there are other places like this.
My ideas on this would be,
first, to possibly divide this into regions, perhaps by a "poll".
second, child or no child
Third, the cost
Fouth, how long, a day trip, a weekend?
Just throwing ideas out there for you.
In the winter, there are many huge houses with a lot of bedrooms in them to rent at the shore. That's another possibility, but get a guaranteed number and the deposit. Little bit tricky here. You need to trust the person that you are sending the deposit to. Something to work on.
I have also been to family reunions, where they rent a pavilion in a park. Also would include BBQ equipment, very low cost.
High end would be reserving a block of rooms at a hotel. Need to tell you a funny story about my trip to Canada. We had gone to the Hard Rock cafe for dinner. Everyone had paid for dinner already, and most got into groups to go out for the night. Not me. To cut my cost, I went with a roommate and that roommate had a 2 yo so we went back to the hotel. That was OK, because they were having an animal show at our hotel and the 2 yo loved it. But getting off track here. So 2 people had stayed around to wait for the waitress, and settle up the bill. They left about 10 minutes after we did. Remember this was an abuse forum group that I was with.
When they walked out of there, O J Sim pson was in the waiting area, with all of these people wanting to get his autograph.
I just wish you a lot of luck with this.
Hope if things work out, there might be one close to where I am.
((((((((((hugs)))))))))
amy