I love to have Winterfest Eve as well as Winterfest. For the eve, I have them put up their decorations and do the tree, clean the house, invite friends over and get in the festive spirit. Father Winter also appears. Then the day after they exchange gifts, have a sing-along round the tree and a grand feast. Then they will play out in the snow.
Irl it is my favourite event of the year and I'm happy I can let my sims do it too.
Being from the UK I also like to do Bonfire Night, but it usually ends up being a bit lame in game. They visit a park and gather round the bonfire for stories, grill some baked potatoes, play with sparklers and set off fireworks. But no other sims ever come and join in. I'd love there to be crowds like irl. I guess I ought to try and time it with whichever festival does the fireworks and go there.