Definately Christrmas Vacation, the general concept is so true to life, I look forward to having all the family round for a good old traditional family christmas then usually spend the xmas day and boxing day wishing they would all go home!
There''s another oldie I like, I haven't seen it for ages but I think it called Yes Virginia, there is a Santa Claus, it's about a girl who writes to the newspaper asking if there is a Santa.