If powder is your number one criteria, stay flexible. We recommend booking flights on Southwest Airlines so you can change flights with no penalties. Also, most rental car companies and hotels will allow you to change or cancel your reservations provided you do so with adequate notice.
Remember, powder is awesome, but there are lots of other reasons to choose one destination over another. Think about convenience to airports, hotel options, and other opportunities like horse-drawn sleigh rides and snowmobile rides.