Most of the holidays will have basic decorations set up on the day such as lanterns and candles. I'm going to avoid adding NPCs and instead use the method from Wet and Cold/Run For Your Lives to move already present NPCs to appropriate locations. Mods which populate Skyrim with NPCs will be recommended. I may also use the equipment switching from Wet and Cold to modify outfits (such as festive hats, toy swords).

I currently have non-merchant NPCs crowding into temples throughout the day and it works fine. After 5pm the rest close their shops early and join them, which is pretty neat. I thought I'd have more trouble setting that up but it works well. As usual compatibility shouldn't be too much of an issue as I won't be modifying NPCs directly and unless a city/village mod is moving buildings around, there shouldn't be many issues with decorations either.

Anyways I'm posting this to gather feedback, ideas, city-specific lore stuff I may not be aware of. Everything I posted is subject to change. The plan was to get this released before the holidays but I'm not sure if that will happen as I prefer to release my mods fully fleshed out.