just watched a bunch of youtube 'learn to ski powder' videos which are all really just promos for their respective Cat and Heli guided trips. From the videos, it looks like most serve up pretty shallow powder (1 foot) on intermediae slopes to fairly pedestrian skiers and that 'powder lessons' are a big part of the experience. It seems regardless of skill level, the heli outfits are designed to get just about any skier a slid powder experience
I think it's a pretty specific set of outfitters who are putting folks in 'waist-deep' snow and an even more specific grop of skiers who really want that.
My advice:
1. Get a hold of the Deslaurier's ' Ski the Whole Mountain'--it was a game changer for me, lots of familiar Ideas if you already like PMTS, but with a few focused tweaks that just make a lot of sense and are fairly easy to put into practice (also, the whole segment on 'Pedal Hops and Pedal Carves is worth the price of the book, that taught me more about maintaining flow in real steeps than any other technique I've attempted to learn). GReat photos and step by step instruction.
Nothing replaces time in the snow-but you need to have a plan of attack before you head out...I suggest the one spelled out by Eric and Rob Deslaurier.
2. What everyone else said, what you need is a FLEXIBLE SCHEDULE. No matter where you ski, you get powder days, the key is you have to be able to take advantage of them when they show up. Often, smaller, more off the map ski areas (in the east we're talking about) are better because the powder hounds and the crowds don't sniff them out and you can find unbroken lines late in the day (especially on weekdays). I ski mostly at a small (1100 ft vertical) Massachusetts mountain...check many of the videos I posted, it get's powder days and typically, you don't share it with very many other people (in a good year I get 10-12 days over 6 inches, with 3-4 serious storms, even the occasional 30 inches-and I usually still ski unbroken lines all the way to closing). If you can get up to nothern, VT or Maine, you do even better. But really you have to watch the weather and let work/ family know, 4 inches or more falling within driving distance-you're gone.
3. Deep Powder...good luck getting enough time, That truly bottomless feel is something really hard to find at almost any in bounds resort: The Pacific Northwest can deliver (but bottomless at Mt. Baker maybe one of the few times even a good skier will think 'man, this is too deep!') and a pineapple express in the Sierras is something to behold, but that's the stuff legends are made of.
The Northeast gets it once in a while in bounds with the help of wind drift after a Nor 'easter. (Once at killington I made 1o-15 turns in waist to chest deep snow off the side of outer limits), I've had the occasional 3 foot of snow, but I think you got to go hike and prowl with guys like bushwacker to find truly 'deep' snow consistently in the east.