I've watched Lethal Weapon again several times over the years and enjoyed the Christmas-festive elements. I love Lethal Weapon 1, 2 and 3.
It's a Wonderful Life is a great movie, especially over Christmas. But another often overlooked Frank Capra classic I love at least as much is Meet John Doe, starring Gary Cooper and Barbara Stanwyck. For those who don't know, it begins with a newspaper being taken over by a rich politician and firing a bunch of staff. One of the fired columnists (Barbara Stanwyck) fires off a fake letter to the editor before she picks up her last paycheck, the letter signed an anonymous "John Doe", protesting politics and the state of civilization. It sets off a firestorm of controversy so great that the columnist is re-hired. And they hire an unemployed vagrant (Gary Cooper) to pretend to be the John Doe figurehead for a regular series of columns protesting social injustices, that grows quickly into a Tea Party-like national movement for the "average American".
And it all culminates into a beautiful moment at the end on Christmas eve.