MacThayer has the right idea. It is also important to get a good quality of flannel, with a durable weave. I use flannel on both frpnt and back from time to time. My preferences, however, are corderoy or brushed denim, both of which give you a soft feel but have more body. Flannel, however is not ideal for FMQ, as it may tear on the stitching lines unless you have a really good quality.
The quilt I currently have on my bed is really good flannel on both sides and has FMQ.