For baby quilts/receiving blankets I've often used just two layers of flannel.
For family quilts/throws our preference is often for just the pieced top and then a layer of fleece as the combination batting/backing all in one.
If a warmer quilt is desired I will frequently use the fleece for batting and then flannel for the backing.
Can you tell I love the snuggly softness of fleece and flannel? Lol!