C.S.
We are planning an extended family vacation this year as well, and I'm hoping that we will go to the Wilderness Resort in Wisconsin Dells. We haven't gone there with our extended family, but have gone 3 times ourselves and love it! It is a great place for families to go. They have 7 or so waterparks that are only open to their guests, plus other fun things to do as well.
Hope this helps!
C.