I want events that take longer than half an hour to finish.
Take Halloween for example I liked that you had to log in daily to buy candy and grow pumpkins for items. It gave us more things to do leading up to the event/they just need to expand on the lead up to events more. It adds to the atmosphere as well, it's like irl how we put up a Christmas tree a month before Christmas to get into the spirit/but in animal crossing it kinda was a one day type deal.
I also just want more items!. So many of the events to me have felt a bit lackluster with the items. We don't need more wands!!! and if we could have rugs, wall items, garlands etc outside there would be a wider appeal for some of the items. Wedding Day is a good example of this for me, the set whilst nice just wouldn't work for my islands theme at all, but the bouquet of flowers you can hang on the wall would look amazing around certain areas, but instead it's just another item in my storage.
I don't want to be greedy when I ask for more items, but like if you see the Pocket Camp update that has 50x more items at the same time as the NH update... well it'll make you jelly!.