As sdianel stated above...consider giving them plane fare for their Christmas gift (you can get good deals if purchased early) and have them visit you in a warmer place than Michigan.
Consider what exactly your 'at home' holidays consist of. Is it a meal and gift exchange or do they spend many days with you. They're 30+ years old. Perhaps they'd like a break, too.
We lived in Michigan also when we began full-timing. One year we just left the RV in Gulf Shores and drove back with only the vehicle for the holidays. We had absolute terrible weather going and returning. The kids were working and that time of year was hectic for them with gift shopping, wrapping, parties they wanted to attend and added meal planning for us. We didn't do that again. We were relieved and I think they were, too.
The older we get the less enthused we are about the holidays and all the pressure the stores put on everyone. That's not the reason it should be celebrated. Doing so much simplier makes you feel better. Perhaps suggest that they volunteer at serving meals for the less fortunate to fill in the time.
Good luck with your decision.