I often times use flannel. If I machine quilt, I like a heavier weight flannel or warm and natural as it stitches better. Wall hangings and table runners are a great way to use piece batting as well.

I use warm and natural too

I use Quilter's Dream Poly for all my wall hangings. It has enough loft to give the quilting a little definition but is still nice and flat. It's also lightweight so it's less likely to sag over time.