I make them a variety of ways (for my own use) because we seem to like different thicknesses for different things.

I use one of three setups:
Thin - layer of insul-brite only
Medium - layer of insul-brite and one layer of cotton batt
Thick - layer of insul-brite sandwiched between 2 layers of cotton batt (3 batting layers total)

The thin ones are great for wrapping around a bowl out of the microwave that is only a "little" too hot for bare hands - I make these ones larger than usual and they can also easily be folded in half if a thicker potholder is needed. These get the MOST use in my house.
The medium ones are good all-around all purpose potholders and also serve well as trivets.
The thick ones get the least use, I use them for things coming out of the broiler and also as trivets sometimes.

I got off my duff and made myself some new pot holders last week. The new shaped ones are pot pinchers and the others are Have a Heart pattern. The thing I like about the hearts is they have a cording on the edge of the pockets that keep them from bowing out of shape.

Update on my pot holders...
 

I finished my pot holders a while ago and have been using the every time I cook! I really appreciate all of the cooments and tips from everyone. I made two different sizes and thicknesses - one for stove top and one for oven. So far, I find that my favorites are the 8" ones with 2 thicknesses of "Wrap-N-Zap"...these are very flexible and provide enough insulation. My husband also does quite a bit of cooking and he was actually the first one to use them...I thought he would think they were too fancy and grab one of the old tattered ones instead...He likes them as well!

I use insulbrite and one layer of cotton batting. But don't like how stiff and crinkly they are. No burned fingers though!

This is what I've done and everyone has seemed really happy with it. I used the craft size package and it was nice and thin and not too crunchy and glue stick baste. Its a pain to baste and was the worst first hand quilting experience ever, but I was happy with the end problem.

Actually I totally lied. I only use one layer of warm and natural. The insulbrite goes on the outside of the potholder and the cotton goes inside. I've really enjoyed using the mitt I Mage myself this way