So far, I do not see anything on the FS Vail, Jackson Hole nor Scottsdale websites about a resort fee but from my source it is on its way. However, the language on the website has been modified to include a resort fee:
Rates are per room, per night and do not include applicable taxes, service charges, levies, resort fees or surcharges, unless otherwise noted. Rates are subject to change.
I would book now to avoid any potential resort fee as if you book they announce it the hotel cannot assess it post hoc.