We always have a stress free christmas 
Tree and decs put up around 2nd week in Dec by my own children and the mindees - I don't rearrange anything, just leave whatever they have done (has been a touch hit and miss lol)
Then we start on christmas eve with a trip out somewhere, come home and have chocolate and alcohol, boys in bed (new pj's of course) then pressie wrapping.
Christmas day we get up, open stockings, mooch about for a bit, eat croissants and drink champagne, grandma comes in to open pressies, drink more tea/coffee, eat more chocolate, open more pressies. Play with stuff, watch tv. Mid afternoon/early evening we eat whatever - usually cold meats and salad with new potaotes and more chocolate (oldest son has pizza :)) then we slob some more.
We don't invite anyone in (except grandma who stays for an hour or two then goes home), we dont go out (unless we have a new outdoor toy), we dont get dressed (unless we are going out), we dont cook (unless you count the pizza lol), then we have showers and go back to bed. Lovely!
We have done this ever since we had the children. Its the one day each year that we are all at home together with nothing to do and we love it. When the boys were small we did all the reindeer footprints, santas magic key, mince pies and stuff for FC. We always had a "party tea" of the childrens choice and then we had a romatic dinner for two when they were in bed. Now they are teens they are up later and we might play a game or two.
Christmas is what you want it to be.