Good question.
From my own personal experience, you probably have to own two suits. One for milder climates and one for extreme cold. One thing I learned over the years, is that Gore-Tex and Thinsulate work very well together for colder, windy, conditions. (A hood is a God send as well!!)
I picked up a Rivers West hooded jacket this past season and while obvious it's waterproof, it isn't insulated. I wear this jacket with layers for bowhunting. Can't stand being "bulked up" while trying to draw your bow!!
Cabela's whitetail extreme clothing line works well for extreme cold conditions. They aren't cheap, but when your outside in cold conditions, you can't skimp on cheap stuff!!