*If* you are going to do a meet in the West, it needs to be at a place with decent access. Salt Lake City area being the best all around imo. Flights are reasonable and it's less than an hour to most spots. About an hour to the Snowbasin/Powder Mountain area. Lodging options are a lot more reasonable too.
Other spots with good access. Colorado/Denver areas, Tahoe (Reno/Sacramento for airports), Seattle and Portland spots. You'd probably have to work a little harder on lodging and logistics in the PNW. Lift tickets are some of the most reasonable in the US though. Bozeman MT would be another place to consider. Not sure if Idaho has good airport access to their good spots or not.
Mammoth has its own airport and shuttle service as well so it is pretty accessible. It's also a mid point in CA since Tahoe is a little further north. BUT I have a friend who works on the Tahoe mountain so maybe that could be something to work out with him. Like I said, I don't organize well lol