We only ski for 3 days, so one large resort is OK for us.
Really? Do you take days off from skiing or is it less than a one-week trip? If the latter, I'd be inclined to go somewhere with clean access, like Utah or Tahoe, vs. a remote place like Big Sky or Telluride where you chew up a day or 2 just getting there and back. At Utah or Tahoe I'll bet you can squeeze a 4th ski day out of this.
Does not get a lot of mention here in the days of gnar but have you considered Sun Valley?
This might be a very good snow year for them and they seem to have everything you have mentioned.
The reason Sun Valley is light on snowfall is that it is blocked out of prevailing west-to-east weather coming from the PNW. Its biggest storms come from the south, usually hitting Tahoe first. So Sun Valley is neutral to La Nina. It's 2nd highest snow season was the record El Nino of 1982-83.
also a la nina winter can be bad for places like utah and tahoe (if this is incorrect please feel free to interject.)
Wrong. Both regions are neutral. Mammoth (150 miles south of Tahoe) is mildly negative.
The bulk of the group is in the "solid intermediate" category.....One of the better skiers in my group stated that she felt Big Sky was tougher than Jackson.....She did mention that the conditions were pretty rough when she was there though, possibly influencing her opinion.
My observation is that Big Sky/Moonlight is a very stratified mountain. The gnar up top is every bit as scary as Jackson, maybe more because with 2/3 as much snow there's a lot of rock showing. The intermediate runs, with the exception of the front side of Andesite and Thunder Wolf, are on the flat side at 5-1 or greater length to vertical vs. the mainstream 4-1 at places like Vail. So the "solid intermediate" in my mind fits squarely into Big Sky's terrain gap. In Big Sky's favor is that the La Nina should help their sometimes lean snow outlook, though the data says Bridger gets a bigger boost from La Nina than Big Sky does.
Telluride used to have the stratified mountain reputation, but the Prospect and Revelation expansions have made Telluride a much better place for advanced intermediates than before. Good choice for a 3-day trip as long it's not too difficult getting there.
I skied Squaw almost exclusively while getting my wife and kids into the sport, and getting myself back in. And IMHO, one of its strengths is the availability of multiple lines, ranging from blue to black or double-black, that share a common start and end.
I agree with this to some extent. "Solid intermediates" should like Squaw better than Big Sky, though lower intermediates would definitely prefer Big Sky. Low intermediate runs are busier at Squaw and can be a real zoo on weekends.
Louise can be brutally cold in early February, but as another contributor noted, the scenery is amazing. ...That's funny, one person mentioned the brutal cold there and said that's the only place he's not willing to go. It really doesn't bother me when I'm dressed for skiing though.
By my observation (and I'm in western Canada every year since 1997) you move the whole temperature distribution curve down 10F or so vs. Utah for example. So you spend a lot of time skiing at 10-15F, some time skiing in single digits. You'll be less than 0F ~5% of ski days by my experience, most of which is in your early February time frame. Lake Louise is relatively uncrowded for a big mountain (only Big Sky on your list is less so) and its lean snowfall rates to get some help from La Nina.
I realize you only have three days, and not necessarily interested in a twofer, BUT I'd like to recommend a look at Powder Mt. and Snowbasin in Utah's Ogden Valley.
Also a good choice for 3 days. And since it's so close to SLC you might get 4.