I'm not likely to show up, but I'm sure not gonna let that stop me from chiming in! Thoughts in two different directions...
1) Snowmass. Like everyone is saying... Big, cool mountain. Plus I've heard that there are real lodging deals to be had there vs Aspen proper.
2) On a totally different tack, someplace like Grand Targhee. A minor pain in the butt to get to, but it has a few redeeming features. It is a fun mountain with tons of on and off piste opportunities. Great place to learn to ski off piste - in powder & trees. The kids area is a actually a great adult novice (and even intermediate) training ground for little bumps, tree skiing, etc. - how could you go wrong with areas like the Eyeball Forest, Bobsled Run, Humpback Forest, North Pole, etc? (trust me, it is all a hoot). Not sure if they'd be OK with masses of grown ups in the "kids" area, but it really is a great set of tuned learning areas. While the lodging is pretty careworn, it is tough to beat price-wise. And lift tickets are a total bargain. You could probably reserve half the Teewinot Lodge and just make it a big encampment. Lift tickets are $55 a pop this year. Compare that to Snowmass, etc. Yeah, I know what you get for an Aspen Snowmass ticket - but Targhee has more than enough to offer for 3-4 days of lessons.
I was super impressed the one time I skied Snowmass. But I bet that if Targhee was onboard, you could do tickets+lodging for half to two thirds what it would cost to do Snowmass (unless some guy heading up ESA coaching can pull some amazing discounts out of the Aspen air
And then there's the Gathering... if it follows on the heels of ESA, Colorado would have many nearby Gathering possibilities. If ESA were at Targhee, the obvious Gathering candidate would be Jackson (again, but sans Tram).
Time to end the ramble...