K.B.
We went in May and loved it!
We stayed in Fish Creek. I would stay there again or more up north.
I would personally go for a Cabin or Condo. It can get pretty expensive eating out and the food is a lot higher out there. We ended up buying groceries in Green Bay and put the cold stuff in a cooler.
I would recommend hiking at one of the State Parks, especially any near a bluff. Peninsula State Park has a trail called Eagle Bluff. It was a fantastic hike with an amazing view.
This website helped me out a lot.
http://www.doorcounty.com/