Hi Robert,
I always reach out to people who book in December and confirm if they would like and feel comfortable having Christmas decorations in the properties. We have never had anyone say no, even if they don't celebrate Christmas. Everyone appreciated being asked and they all enjoyed and were raving regarding festive decorations.
A little tip: We keep the tree decorated year round to save time. Normally ( because of the size of Christmas tree and number of ornaments) it takes over 4h to set up. Since we keep it decorated, only minimal sprucing up is necessary and it takes a lot less time. Since we have multiple properties, this is much more time saving and cost effective.