Hello from Mascouche Quebec
Welcome to DC! I like the idea of a taco bar and pinata. Maybe a cookie or cupcake bar with so many little ones? Bake or buy unfrosted cupcakes or cookies and set out a variety of frostings, sprinkles, chocolate chips, coconut, etc. for the kids to decorate. If you have leftover Halloween candy, you could freeze it, chop it up, and add to the topping mixes.
A baked potato bar is also nice. A bunch of jacket potatoes in a roaster, along with toppings like bacon, butter, sour cream, shredded cheese, chives, taco meat or chili, etc.
She who dies with the most toys, wins.