Well Steve, until someone from the area replies with more authority, I'll try to help.
If the resort's busy, the Shoshone units are too, with traffic in the halls, etc. I can't recall how thick the walls are. We've stayed there years ago and had no complaints. Be sure and get there when the Spring off-season specials start, it's a bargain and usually the skiings great. It has it's own parking lot adjacent, but it's pretty much poached out, so don't expect to get a place unless you arrive in off hours and leave your vehicle in your spot.
Yes, the Huntley area is pretty deserted in Summer. My friends who own places there have seen significant appreciation in the last 5 yrs., so while I don't know how much turnover there is, there's probably some profit-taking going on now. The Bighorn and Arrowhead units are all getting old, many remodeled and updated, many aren't. There's new construction in the Cedar Creek complex that's within walking distance of the base. We rent there and in Arrowhead a couple times a seasonDon't neglect Moonlight Basin, there's apparently lots of new stuff going in there.
A really fine guy--for a Realtor--is Tim Cyr @ Sotheby's Intl. Realty. Graduate of the University of Bridger Bowl, been there for years and really knows the market. Tell him Dave from Northern Masters sent you and he'll buy me a drink.