As a hand quilter, I always think, what will make it easiest to quilt? If you are considering hand quilting it, I would use paper. (I like the phone book idea.) The more bulk you can remove before quilting, the nicer your stitches will be and your fingers will thank you too! If you are machine quilting, I would go with thin fabric. It will save you tons of time since you won't have to remove all that paper. Have fun on the project!