I'm an Level 3 cert instructor in the Northeast at a major ski area and I also have many cat skiing trips to the west under my belt.
For the original poster that started this thread I would suggest the following
Do not go cat skiing with out first gaining powder experience elsewhere. You will fall and be much slower than the group and that is not a fun experience for you, your cat group, and your guides.
I'd first have to question how you can be an advanced skier in the east with no powder experience at all. This winter watch the weather and go chase after some storms so you can gain some experince before going out west. Jay Peak has got pretty reliable powder. Take some lessons in the east with a Level 3 cert instructor and ask them if you have the skills to handle deep powder and develop your skills.
I would suggest a place like Grand Targhee for your trip out west. It is not a crowded resort and has the most realiable Powder that I know of. Take a lesson in the powder there. They also have a early tracks program where you get 1.5 hours of powder skiing before the lifts open with an instructor as a second step. If towards the of your trip you are feeling confident in skiing Powder they have a Cat that has a its own mt to operate on and you can graduate to that thru a nice progressive of skill development.