Your custom holidays

I'm really curious to see what traditions are going to be included in the pack, that's going to determine how creative we can be with the holiday system. Though I'm sure the modding community will add a ton of traditions. I'm a bit sad that it seems we can't specify for the traditions who can do them and to whom. We could for example make a mothersday if we could specify that children give gifts to their mothers or more generally to female adults, for example.
We can create an April Fools probably.
I'd create a summer vacation multiple days in a row where kids don't have school and do summer activities.
I can't think of anything more creative right now.