We have lock-ins about twice a year and the kids love them. (Why they want to sleep in a gym-I will never get) We do crazy relay races since the gym is big enough. We have also used "Belly Bumpers" which are about $40 each, and they look like sumo wrestlers. They love that! I have also done Nerf wars, where we gather everyone's nerf guns and all the foam bullets we can find and let them have at it! The tie dye sports bras is a great idea, and depending on age making hair bows for special practices or choreography camp is fun. Decorating flip flops with tied ribbon is a great idea, and they can wear them around the hotel for out of town comps. Wal-Mart usually has flip-flops on sale this time of year for about $1. If you have room to eat, we buy a new piece of gutter material from Home Depot (about $8 and 10 feet long), place it on a table (prefer outside) and fill it with ice cream and give them all kinds of crazy toppings and they make a huge sundae! (it sounds weird, but it works)