Firstly, does your DS stay up late!? Do you intend on having birthday celebrations for him during the day, or a party? I honestly, would go to the Xmas party. As you say, you don't get to go out that often so why not make the most of it. You can use it as a celebration that you became a mother 2 years ago and YAY for you! I'm sure you will have pleanty of fun and other celebrations with your DS and that will make him feel special....but really, what do 2 year olds do at night...sleep! Go out and enjoy