My rule is 'if you still beleive in Father Christmas hang your stocking outside your door and he will come and fill it with nice things'
At Christmas I will have dd 23, ds 18, ds 14 and they will all hang their stockings and swear blind that they do beleive. They wouldn't risk saying that he isn't real!
contents - socks, underpants/knickers, body spray, toothbrushes, minature perfume/aftershave, a magazine, chocolate coins, magnets, pencils, pens, rubbers, keyrings, minature alcohol (age permitting), tippex mouse, gloves, face/hair mask, vaseline, expandable flannels, jewellery.
I did think that the saddest part of the children growing up was not putting the mince pie, whiskey and carrot out. 
Or do others still do that?