long long ago (in my pre-frequent-flyer-life), about in 1989, on Thanksgiving-evening (only Europeans can get the idea to fly on such a family-date) we flew with UA from LAS to DEN. We were not more than 4 passengers, all seated in eco as we have been "told", when the Steward invited all of us to join the crew (I think they were 6 or 7) in firstclass to celebrate .... It was my first life-thanksgiving - since then I am a UA-client.