Never on Thanksgiving
While the rest of the nation is bemoaning and protesting the intrusion of Black Friday shopping into Thanksgiving, it's against the law in several New England states that still have Colonial-era blue laws that prevent retailers from being open on Thanksgiving.
I'm against religiously motivated Sunday closing blue laws that enforce the Christian sabbath on non-Christians (for Jews, it's Saturday; for Muslims, it's Friday), but for a national family holiday like Thanksgiving that almost everyone celebrates, it's a good idea to ban by law Walmart, Target, Toys "R" Us and other big-box stores from opening.
No one store will stop its creep toward Thanksgiving openings as long as its competitors are taking the advantage. That's why we need a law regulating all stores. The Utah Legislature should take up this idea in January.