Instead of backing the blanket/quilt with flannel or other cotton, use polar fleece.
The first time I made this way, my mom told me I was crazy to use stretch fabric without a stabilizer. Since I finished that blanket, we both swear by it for anything small enough that we don't have to piece the back.
Pros:
1) It's REALLY warm, even if you don't put any batting in. Want it even warmer? Use batting or a second layer of fleece.
2) Unlike cotton, fleece retains most of its insulation value when wet. I haven't field tested too rigorously, but what experience I do have with these in the rain says that if it's damp and you wrap up with the fleece side towards your body, it will keep you warm even if the other side is cotton.
3) It's soft and washable.
Cons:
1) It is stretchy fabric. I recommend that you pin it really good before quilting or tying, quilt or tie at a maximum of 14" intervals, and if you're quilting, be aware so you don't accidentally stretch or warp the fleece.