Go to the dollar store and get plates, cups, napkins. They have different colors and some "themes" like flowers, birthday balloons, etc. They also have games like pin-the-tail on the donkey that the kids can play and stuff you can put in goodie bags, if you are doing them.
And I've found that scavenger hunts always go over well. You can write or draw clues on pieces of paper to lead the kids around the house/yard until they find the "treasure". It can be candy, toys, bubbles, etc. The dollar store has lots of stuff you can get to put in a treasure chest and what they get out of it could be considered their take-home goodies.
And
HERE'S a link for making a paper bag pinata. It calls for lunch bags so kids can make their own - which would be a fun activity for the kids to do - but I don't see why you couldn't adapt it to use a full-size grocery bag and make a big one for the kids to whack at. Again, what they get out of it could be their take-home loot.