I have added a couple of clay flower pots on their sides, pieces of wood or dowel for the chicks to perch on, and lately a wood planter turned upside down. My Americauna chick likes to fly from the top of the feeder to the top of the waterer so I added another destination for her. (The other chicks are very curious about what is up there.)
I handle them for a minute each day letting them loose only when they are calm - a dog training trick I hope also works with chickens!
With all of the toys, water changes, welfare checks and learning how to be chickens they seem quite content. Remember to disinfect and dry anything you put in the brooder.