Speaking of Utah (And probably CO. too) Conditions will be totally dependent on Mother Nature. There could be great snow, or there could not be great snow. As long as it's cold, there will be plenty of man-mad schtuff to ride on.
As far as the City / Town is concerned in UT: If you stay in Salt Lake, you have access to 5 world-class resorts within a 20-30 minute drive (if you have a car) probably double the travel time if using public transit, but still the opportunity to hit all of those resorts. There are also two other resorts within those boundaries, but they don't allow snowboarding, so we won't mention them. Also within about an hour's drive from Salt Lake are 2 more excellent resorts to the North.
If you stayed in Park City proper: Access to 2 resorts and all the distractions the girls could want, all easily accessible via public transit fairly quickly. (Again we won't mention "that" resor that doesn't allow our kind.)
Also keep in mind that Salt Lake is around 20 minutes from the airport, and Park City about 40, so once you get off your flight, you're pretty much there - no long travel times to the resort.