I'd love to take a big group back to the USA, but I've found the price difference to be prohibitive.
We took a group of 10 to Jackson Hole in 2005. But it was so much more expensive than Europe.
The two big differences are the free places you can get with a big group in Europe and the lift pass cost.
Brochure prices look ok, you'd expect a US trip to be more, but you can't get anywhere near the same discounts.
For example I'm taking 30 people to Meribel in January, for £720 a head, including pass, catered chalet, flights, transfers, taxes etc. 6 free places and 2 for 1 lift pass deal means a 30% discount on brochure price.
Try to get something similar in the US and it's 1.5 free places at best and full price lift pass. Places at £1200-£1500 per person are very difficult to sell.