You can't book powder, you've got to chase it!IMO, the best way to ensure powder turns is to make no plans in advance and simply go wherever it is dumping (or at least has the best looking forecast). I'm assuming you'll want to book your airfare early to save $, so the key is to fly into somewhere central where you have the most options and the shortest drives. I'd recommend Salt Lake City. Not only do you have a great chance that Big/Little Cottonwood are getting pummelled, but you can get to Jackson and Steamboat relatively easily (4-6 hours). If you are willing to road-trip, you can probably get to just about any resort in the Western U.S. with no more than a long day's push if the roads are good.
Set yourself up for success by getting a good road atlas (also means you don't have to waste time finding one when you get here) and planning routes to any resort you could conceive of driving to out of Salt Lake (this is where you find out how bad you really want those powder turns). Then print off the central reservations numbers and snow report numbers of all of those resorts. Right before you come, check the internet to see who will be getting the goods. When you arrive in Salt Lake, confirm that it is still dumping where you think it is, jump in the car (make sure its got four wheel or all-wheel drive) and go! Be sure to bring a cell phone so you can make your reservations while you drive. If it quits dumping where you are at, start calling snow reports until you find out where the snow is & move on.
If you chase storms instead of booking in advance, you'll have a much better chance of getting the goods. The quantity of turns you lose to travel time will more than be made up for by the quality of the turns you do get (and the adventure of getting there). More importantly, you won't be sitting at the 'Bird wishing you were in Jackson, or vice-versa.