Hi tick.tock! It sounds like you've weathered the storm pretty well so far.

I've always found it easier to go to my mother than to have her in my house for long periods of time, personally. If you visit, you have a little more freedom to come and go. That's just my take, though. I could also see how being in someone else's house might be more stressful for some. It really comes down to what makes you more comfortable.
Another thing that DH and I have done is split the holidays and spend one (Thanksgiving) with his relatives and the other (Christmas) with mine. Again, that doesn't work for everyone, but it has helped us. I've also tried to set up activities (like movies and outings) to keep folks busy and less likely to sit in tight quarters for long periods of time.
Hang in there! Hopefully everyone will keep the peace for a little longer.