I can't comment on any particular resort, but I can give you some basic information. Hopefully, ColoradoBelle, who is from Colorado and used to be in real estate there, will join in with some more specific information.
There is a saying in Colorado: "Winters are wonderful, but summer is why we live here!" Although the Christmas/New Years holiday season and Feb-March are their busiest periods, there is always a lot to do in the mountains, and something for everybody.
Because September/October are probably their slowest periods, there are often a lot of special deals and community events like festivals going on. There is also horseback riding, fishing, rafting, hiking, mountain biking (a lot of the resorts keep their ski lifts open for mountain bikers to access the upper slopes), etc. Plenty to do.
With the exception of the Broadmoor in Colorado Springs, most of the resorts available seem to be concentrated in Summit County (Breck, Dillon, Keystone), Vail/Beaver Creek, Telluride, and Steamboat Springs. I have never been to Beaver Creek, Steamboat or Telluride, but friends who have love them all. My favorite place to visit in Colorado is Breckenridge, with Aspen/Snowmass a very close second, but you will find many people who are big fans of the other choices.
There is a ton of information on the Internet, so I'd Google Vail, Summit County, Breckinridge, Telluride, etc. and see what you get. All of those areas have VERY active visitors bureaus/chambers of commerce to make it easy for you to get information.
With all of the deals available during that period, you may find that you come out WAY ahead paying cash for your accommodations and renting points to cover the cash outlay. I would sure check that option.