Everyone who needed to decline the invitation was very gracious when doing so. That does not make for very amusing excuses though, so maybe next year, some will use the Holiday Party Excuse Generator as mentioned a few weeks ago on LifeHacker.
I will leave you with a particularly brutal yet strangely humorous excuse that I generated:
Dear Host,
I am beyond delighted that I will be unable to attend your yearly holiday tribute to every conceivable human excess. I will be meeting with the leaders of the Free world, and thus able to avoid you and your wretched but inevitable rendition of "Have a holly, jolly Christmas." Once the holidays are past, I hope to hurl nasty but highly original epithets at you. Please give my condolences to your party guests, and tell them I feel their anguish. My best wishes for a fruitcake-filled and flatulent holiday.