If you need to plan well in advance I'd echo what others others have said and fly to Portland, Oregon. Timberline, with its permanent Palmer Snowfield and traditional early snows is as close to a full guarantee as you can find in the USA for November skiing. Close by is Mt Hood Meadows and Mt. Bachelor could well have good snow by then also and is only a few hours drive further South.
The other pretty safe option would be to fly to SEA/TAC. Drive North to Mt. Baker or further North to Whistler.
There may be great Thanksgiving skiing in many places this season. Let's hope so.
If early planning isn't a requirement, then I'd say follow the weather conditions and hopefully you will find a great area that you really want to ski that has plenty of snow by Thanksgiving. If Colorado has good early snow, its lighter snow would edge out the PNW in the minds of many skiers.