I am the oldest "child" of the youngest generation of my family. The others are aged 9 to 17. In previous years we all go to my maternal grandparents house as a big "family" celebration. We ate amazing food and still did the "Santa" pretence though the youngest figured it out a couple of years ago 
This year cousins are spending Xmas with their other grandparents, so my dad has decided that we wont go to my grandparents either, but spend Christmas just us.
It's just not going to be the same. My parents are probably going to separate in the near future, so the atmosphere won't be great. My grandparents come from a different country and culture so even Christmas dinner will be different food. I'm not dreading it by any means, but I'm not looking forward to it like I would normally be.
I basically just have no idea what to do or expect at the first Christmas at my parents house (I no longer live there if that's relevant) and also with no children.I'm kind of imagining it like Sunday roast but with presents...but I rarely go home because I find it stressful and upsetting so that's not really an ideal image
I would like to visit my grandparents (who will be alone) but it would be almost impossible and my parents would get offended probably.