Replying to Season in US

After having done one season overseas 06/07 in Whistler, im looking at planning another one for next year (08/09), probably around 3 months and i have decided i want to go to america (I'm from Australia).

After reading a lot of forum topics and internet guides i have come to the conclusion that i really want to go to Aspen, so i was wondering, compared to Whistler, is Aspen really as expensive as it is made out to be?

Would it be worth the money?

Otherwise i was thinking of going to mammoth for a few months.

What are your opinions?
Any other places i should look into?

Im looking for a place with Heaps of terrain so it doesnt get too crowded and the majority of terrain i would be skiing would be difficult/expert (not being a dick who thinks he's awesome, just saying i wouldnt be skiing much intermediate stuff)

Any adice/help would be great.

cheers