My family and I always celebrate Christmas Eve on December 24th and Christmas on December 25th. On Christmas Eve we used to visit my maternal grandmother, we always did that ever since I was a little child, but after her death, my uncle who lived with her all his life continued this tradition and now invites us over for cake every year.
Afterwards, my parents, my brother, my godmother and I have dinner at our place. We usually have our little giving of Christmas presents beforehand.
On Christmas Day my paternal grandmother used to invite our entire family (and it's growing steadily) for coffee and cake and dinner. It's always been an incredibly nice gathering (and so much stress for my mum because it was always held at our place since my grandma used to live upstairs). However, when my grandmother died in 2005 my parents and aunts and uncles discussed how to celebrate Christmas Day and thought of a rotating system to share the work. I, however, stuck to our tradition and convinced everyone to stay at our place for Christmas Day celebrations and so everyone did. There's been a few alterations concerning the menu etc, but Christmas Day is still celebrated the way my grandma would've liked it and that means so incredibly much to me.
As for New Year's Eve, I used to celebrate it with my parents who had invited some of their and my friends, but since there's been a lot of growing up in the past several years, I started to celebrate New Year's Eve with my friends. Especially this year, it seems to be so much more important to celebrate New Year's Eve with my friends because we graduated from high school in March and are off to different cities and universities, so this is one of the nicest occasions to celebrate with your friends.