I would think just the one layer of batting with flannel backing would be pretty warm, but I've read on here where people use two layers, I've never tried it.

I third or fourth or fifth usinf wool for the batting. It's light weight but suprisingly warm.

I live in Wisconsin and also recommend wool for the batting! I use my wool quilt almost all year round...it breathes so is comfortable except for the really hot days/nights.

Personally, I think cotton batting is cold. I've used wool batting and it's just as toasty as can be. Also, I understand poly battings are warmer. Also, the less quilting you have the better because if you can capture some air- think tied quilt- it is warmer that quilts that have been quilted into 'cardboard-ness'.

The quilts I've made with wool batting are, by far, our favorites. As others have written, the wool is breathable. In CA, we use them year-round. Wash/dries nicely too. I wouldn't choose W&N 2-layer for a king sized quilt.

I to am from Wisconsin, down in a low valley area. We are always a tad colder then normal areas. We have the heat shut off in our bedroom (as we like to sleep when it is cold) and seriously the temp is normally 58. We have just one quilt on our bed and a very thin blanket. The quilt is made with poly fill and tied.. the one made with W & N..and LAQ...we freeze. So that one is now used in the guest bedroom (as that room is heated) and 66 in there at night. Our son and his wife are always warm.

I made one with double poly and it doesn't wrap around me as nicely as a single layer does. I am a believer in layering two quilts for warmth rather than one heavy one. (And socks are the BEST for keeping you warm.) Good luck and let us see what you do!

You could use a layer of wool and a layer of warm and natural. It comes out very nicely - my Innova dealer/teacher had samples that felt great.

Puff quilts are very warm!
The way I make them is to stitch in the ditch long "tubes" (4 1/4 inch squares finished), then stitch one ditch across the middle, then stuff from the ends a handful of polyfil. (push up w/ yardstick). Seal off each square puff a row at a time...When you finish it is puffy and warm!

Another idea to make a warm quilt is to use an old pattress pad as batting -- these are actually heavy enough to use as beach blankets or "moving" blankets! (protect furniture) if you use scrappies.

Thank you all for the great responses. I decided to go with the Quilters Poly fill. My friend called me back today and said wool won't work because he is allergic. I asked him about using Polar Fleece as batting and he was afraid of the fleece attracting more dust and things. The Quilters Poly said it was allergen safe and 3/4 inch thick so they should be plenty warm. They live in Northern WI by the MI and MN borders and wind chill can be double digits below zero. I'll stay in Sheboygan LOL.
I like the idea of the puff quilt, that may be the next one I try. In January I will have been quilting for 2 years and I am loving it. My mom and her friend got me started. Last week I made a baby quilt in 10 hours with 144 3 inch squares. It truly was fun to do.