Hardiest banana is Musa basjoo. I'm further south, though still in 6b, and have gotten through without any winter protection at all. The banana was killed to the ground, but popped up aggressively in the spring. Alternatively, you can dig up a pup, and keep it in a pot over the winter. Bananas grow very fast.
Elephant ears usually have to be dug up and brought inside, or at least kept in a cool, unheated garage. I've had a few survive without doing anything, but they were planted right next to the house on the south side; I don't think this would be normal.
Windmill palm is the hardiest palm, but I think you'd need some kind of protection for it.