Defo the Great Escape, but I once forced (get social services on me if need be) my now 14 & 15 year olds when they were 9/10 to sit down on Christmas eve, and to stop being so selfish and frantic and their "punishment" was to sit down not move and watch Zulu. They loved it, and still do!
Two very old but great films
It Happened on 5th Avenue and The Cheaters . I recorded them from the television years ago and have been trying to find them on dvd ever since. Another two good Christmas films The Bishops Wife and Since you Went Away.
White Christmas (1954) Bing Crosby, Danny Kaye & Rosemary Clooney, Holiday Inn (1942), Bing Crosby & Fred Astaire, incidently it was in the earlier film in which Bing Crosby first sang the song ' White Christmas'
I love It's A Wonderful Life but I also love the kids classics One Magic Christmas, Prancer and The Wizard Of Oz which was shown every year when I was a child