For the past 26 years my wife and I have been obligated to travel about 500 miles round trip for Thanksgiving and about 350 miles round trip for Christmas.
For Thanksgiving in my opinion it is ridiculous. My in laws are the ones that host, yet live 250 miles away from where they host. Every year they rent a small event hall, an old house converted into an event hall, and everyone goes there. In the beginning the in laws hosted at my mother in laws mothers house that the in laws owned. Once my mother in laws mother passed away and they sold the house no one there stepped up to host. They all just expected my in laws to continue to host and refused to travel.
Christmas is also a little on the ridiculous side. We always go to my brother in laws. His wife hosts a big Christmas Eve party primarily for their local friends and her parents. It was so hard when my kids were little. Having to somehow get all the presents there without the kids seeing. Eventually we started coming home on Christmas Eve getting home around midnight every year. It made for a less than relaxing Christmas morning.
Not once has any of the family we travel to offered to bear the burden of traveling, even on an alternating schedule.
I really wish we could start our own family traditions.
You don't HAVE to do ANYTHING just because other people expect it. The situation you've described is, honestly, ridiculous. Your ILs live WITH you, yet because all the rest of your ILs refuse to travel, you AND your ILs "have to" travel 250 miles away, rent a hall, and put on a massive Thanksgiving feast?
That's dumb. Especially if your ILs are getting quite elderly now. Especially if putting this on every year has become more and more difficult for them.
Nobody can take advantage of you without your permission. This has continued because you have CHOSEN to go along with it.
What will happen if you just say, "Enough. Not this year. We're not going"? Will they all get upset? Probably yes. But you know what? They'll get over it. The people who really want to see your ILs will come to see them where you are instead.
You CAN start your own family traditions. You SHOULD start your own family traditions. Just because this is how it's always been in your extended family doesn't mean that's how it always SHOULD be. Stand up and take charge of your own life.
For the first 11 years of our marriage, DH & I knocked ourselves out every holiday season and we'd travel to go visit my ILs for 1 holiday and then my parents for the other holiday. My ILs and my parents did not live in the same area and it was about a 5 hour drive in opposite directions to see them from where we lived at the time.
Then we moved to another state and had kids and you know what? We could totally not afford to travel. Nor did we have enough vacation time in order to travel. So I told everybody that if they wanted to see the grandchild and see us, they'd have to come to us. My parents were really ticked off about it. But they got over it because they wanted to see their grandchild, so they sucked it up and dealt with it. And the world continued to rotate on its axis. Everybody adapted and got over it.
When the kids were a little older and we actually had vacation time, we started to travel occasionally at Thanksgiving to visit 1 set of relatives. Except for ONE Christmas, we've always celebrated Christmas at OUR house. WHY? Because I was just NOT going to deal with the nonsense of getting all of the Santa gifts sent to a relatives' house so my little kids wouldn't see the Santa gifts in the trunk of the car. My parents were regularly mad about that, but again, they got over it when they saw that DH & I were not budging on this.