I haven't been anywhere besides Red Lodge but since I live in Montana, I know what resprts have the good snow. I went to the local ski shop the other day and they had the resorts listed by "Best Conditions". I know Whitefish ,in northern Montana, has the deepest base and best conditions in Montana. Big Sky, Bridger, and Moonlight, which are all near Bozeman have good conditions. Grand Targhee is in Wyoming but it's still in western U.S., and like always Jackson Hole is good.
Hope this helps even though this is all Montana resorts. Still west, though!
You can pretty much always look at the webcams at Whitefish ^ and see that on the North Summit cam it's like a whiteout. Almost a 70 inch base, looks fun!