If your kids are anything like mine I'd choose to have them Christmas Eve and then first half of Christmas Day.
I say this because my DS1 (in particular) goes to bed soooo excited for Santa to visit. They wake me up in the morning and we wish each other a merry Christmas then rush out to the tree together. The magic of Christmas in the morning is just so beautiful. We open our presents and they always truly get most excited at my place. We then go to two more places (my parents are divorced) so even by the time we get to my mum's at lunch they are still excited but a lot more encouragement to open presents is needed by me (particularly for DS2 who is 2 years old).
They are a bit over it all and could quite happily nod off but then it's off to their dad's place. Santa visits there too ... But I could imagine it's not quite the same as the novelty of presents have probably started to wear off. (I do feel a little guilt over this - but not enough for me to offer a change).
I also think I get the best part of their behaviour and attention. My exH gets kids who are tired, who've overindulged on Christmas buffets and treats & a little hypo from the stimulation of the day.
That being said I'd quite happily have my boys aaallllllll day if the ex had an issue with their tanties