Chuck E Cheese is always a hit. Don't eat the food, just find a coupon for tokens and let them hit the games for a bit. My kids love the Bean Museum (and it's free so I love it too)! We also like BYU's Museum of Paleontology if any of them are in to dinosaurs.
you should have an ice cream pajama party! I know there is a way to make ice cream in little ziploc bags too. They might think it's fun to make their own ice cream!
So How was the big weekend...What fun and crazy things did you do?