Ah skiing... If it weren't for our Disney addiction we would do a lot more skiing! We

to ski! My parent took my sister and I skiing every other year since I was 5 and she was 3 until we were high schoolish age. We have since gone with my parents as adults with our son when he was 4 and again at 6 years old.
We have skiied Devil's Head (WI), Keystone, Breckenridge, A-Basin,Copper, Vail, and Steamboat. My parents used to go ever year and have skiied many many other places. Too many to list and heck I can't remember them all. Anyway, since discovering the Keystone area we keep going back! We love it there and there are so many option in that area. Keystone is our favorite, but in the same area (and same ticket) you can ski Keystone, Breckenridge, Vail, and A-Basin. And also in the same area, but seperate ticket is Copper.
We find Keystone our favorite because it has something for everyone! They have the trails for beginner (Schoolmarm) to the back bowls for the experts only. They have many dining options spread out at the base of the mountain and on the mountain so there is usually a place fairly close to stop and rest and warm up the little ones. We also find Keystone much easier to get around. Breckenridge used to be aweful to try to get from one side to the other, but that has changed drastically on the past several years.
Keystone has River Run Village where you can stay right at the base of the mountain (kind of pricey) or you can stay in any of the surrounding mountain towns. We usually stay in Silverthorn or Dillon which is about a 15 minute drive to Keystone and much cheaper.
I have been in ski school many times way back when... and we put our son in ski school/day care when he was 3. I don't remember if we made him go to ski school when he was 6. I don't think we did. He took to it like a duck to water.
At age three when we took him he was a little young. Ski school for him was more like daycare. I believe they also had a purely ski school option also for about the same price. We opted for the longer day the first two days. They would play for a while then head out for some lesson learning pizza wedges and french fries. They got cold fast and if the kids didn't show interest they would let them go in. The "lesson" included lunch and a nap and then they would go out again for some fun in the snow. They did learn and they got a report card each day that said what they did. He enjoyed it and after we picked him up in the afternoons to ski with us he asking if he could do french fries and go fast! My dad injured his already bum knee on this trip so he then decided he would run around with DS to save some money.
At age 6 we had to hold him back. He was a natural and had no fear. We haven't taken him since. We have been going to WDW every year some time twice a year. Every winter I get the itch to go skiing. Last year we went with some friend on a couples only trip and had fun. I don't think DS 12 would let us go again with out him. We thought about going this year but with DS 2 decided to hold off a year or two. I think 2 is a little too young.
Now I have gone off on several different tangents, but to answer your question I would suggest the Keystone area. If you have any specific questions just ask. I can even give us suggestions on where to rent your equipment if you need it.
BTW, I have begun to wonder if we could sneak away for a long weekend just DH, DS 12 and I...