I have backed a quilt with denim, which I quilted by machine. Used a jeans needle and cotton batting. I really liked the way the quilting showed up on the denim, sort of sculptural.
So maybe try a couple of potholder-size quilt sandwiches and see how you like different combinations of batting and backing, etc.
I want to do another quilt with denim to keep in the trunk of my car, but I think it's pretty far down the list right now, and i need to save up more old jeans, anyway.