DH and I used to go out for Christmas Day to the PILs and my parents, we'd go to one for lunch and the other for dinner/drinks and then swap the following year. When DC1 arrived we decided that year we were staying at home as being out from around 10am to gone 10pm was too long of a day. My parents weren't bothered by this (in a nice way, not a don't care way IYSWIM?) and they still had some of my siblings at home anyway. PILs didn't have any children left at home (DH is an only child) and I felt sorry for them when they commented that they weren't even putting up a tree or having a turkey dinner because there was no point when it's just the two of them so I invited them to ours for Christmas lunch.
Over the last few years this has been repeated, PILs come to ours for lunch and then we visit my parents afterwards and we're home by 5pm at the latest. I'm getting to the point where I want to stop it. It's not that PILs are bad people it's just too much and I end up in a right ratty grot by the time lunch is served that I don't enjoy it.
Every year we say to come round at 12ish, we like to open presents in our PJs and laze around eating breakfast and the DCs are still very young so usually have a nap around 10/11ish. Every year they show up at a random time, last year it was 10 o'clock, the DCs had just gone down for their naps and DH and I were taking a chance to thank each other for our gifts 
, FIL leaning on the doorbell was a bit of passionkiller TBH and woke the DCs who tantrumed and whined for the next few hours. We don't smack them but PILs kept threatening smacked bottoms if it didn't stop. I was bobbing in and out of the kitchen switching things on/off and checking the turkey, every time I did I had one or both PILs under my feet. I know they were trying to help but this was after I politely but firmly said I didn't need help, I know what needs doing and when while I'm cooking and having someone doing their own thing with it just stresses me. I had then tasting things with their fingers and adjusting the seasoning, re-whisking my Yorkshire batter, turning the oven and the rings up/down, and then FIL decided to help me plate up by simply chucking food on top of other food on the plates - I know presentation isn't everything but everything piled on top of everything else in the middle of the plate drowning in gravy isn't appetising. Meanwhile MIL starts doing the dishes, standing directly in my way, and insisting we don't start dinner until she's finished. I bought a nice bottle of wine and was BFing so only planned one glass, I didn't get any as they drank the whole thing like it was pop. FIL then made cracks about breasts when I fed youngest DC after lunch about how they like a good tete au tit after dinner and if he'd known that was on the menu he'd have saved room and that DH must be in a grump that the baby got there first and haha bloody ha. We played Wii because it's something everyone can join in and FIL kept shouting at the DCs when it was their turn "left LEFT!!!! Where you going?! Go left! Oh for God's sake!", etc.
On the positive side of it though the DCs do love to see them, they're keen photographers and they take loads of pictures during the day and then give us a disc of them and a few of the best ones framed, they always bring either the starter or the dessert for the meal, and they play with the DCs and their new toys, plus DH likes having them and likes that they're not alone on Christmas Day and they enjoy themselves too. It just seems to be me who ends up fucked off and stressed annoyed and twitchy. I'm fine with them the rest of the year, they just seem to save their annoying behaviour for Christmas.
I never intended inviting them for Christmas lunch to be an annual thing, it was just supposed to be the one year but it was then presumed they'd be coming the following year and now it's years later and all I want is one year just us and the DCs with no visitors and no going out. They can come next year and every year after, I can take it if I can just have this year for us.
DH isn't at all receptive to the idea and says they'll be gutted, that they love coming here for Christmas and we've set a precedent having them all these years we can't just refuse this year so now I feel like a selfish cow for even mooting the idea. I even tried a compromise, they can come this year and we'll have next year as our year to oirselves, thus giving them over a year to make alternative arrangements. AIBU to put my foot down and insist on a just us Christmas just this once?
Also, before it's suggested, going to theirs as a change and letting them take the burden of cooking dinner, etc isn't an option. They have cats and DC1 is allergic, there's no dining table and only four seats in the front room, and it's too cluttered for the DCs to be able to play safely.
Sorry for the novel but I feel better for unloading it all!