A "We Don't Celebrate" button for holidays.

I'd love it if calendars - or at least holidays - were actually per household and not per game. Like, you could set up a default one when you first played, but there was an option to mark on the holiday if it was "universal" or "specific" - and then you could edit the traditions for specific households, like some might celebrate Winterfest with family and Father Winter, while others with lights and remembrance. One couple's Love day could be having a meal and a movie in house, while another could be big on going out on the town on a date and gifts.

I mean, admittedly I don't play on rotation, so it's not something that directly impacts me. But it's still something that would be nice to have in the game.