I'm an avid skier and have skied all over the West from early season to late Spring. I would never count on Thanksgiving skiing at the Park City ski resorts. It is unusual to get more than New England snowmaking and limited terrain open in PC that early in the season. The Little Cottonwood ski areas, Alta & Snowbird, do have good track records for November skiing. PC is situated on the leeward side of the Wasach Mts. and need a different wind direction that starts in Dec. for the great snow I've skied there around Christmas. It is a long trip to go from PC to Alta every day.
My home resort, Timber Lodge is even more of a casino crap shoot for snow in early season due to the low elevation of Lake Tahoe compared to UT or CO. We go there for Feb. or March ski trips. I love the tree skiing there, lake views, and the casinos. A unique combination in ski country.
If you want the most dependable November ski conditions I would certainly advise that you own in Vail or Breckenridge. Take a look at the Silver season there for mid-Nov. and late April. The 8,000 ft base elevations and cold temps. there usually provide at least 40% of all trials open in the early season. Occasionally Vail has some of the infamous Back Bowls open for Thanksgiving. Vail is a great ski town too.
Ski tip: only ski for a half-day on the first day of the trip. You'll be more rested and ready for the rest of the trip.
Eric