I am not married, so no in laws to contend with.
And I realise I am fairly lucky with my family.
We celebrate Christmas Eve, so that is the main event.
Always at my moms, with the whole extended family. A thousand people in the kitchen, making the 3 main courses.
Dinner is always schedules for 9pm, but it is rare we ever start before 10pm (though things are getting better, with prep time starting earlier!). The we open presents at midnight. Years ago, it was a case of one present at a time, and everyone would have to show it off, but now we do several presents at a time, so that had cut down on present opening massively, and usually by 2am we are done!
People do make an effort to dress up, at least slightly (my mom and I go extra, cause thats just who we are), there are no fights, no drama, just food and drink and love! There is always between 17 and 35 people, depending on years, as some of our guests split Christmas with other families.