A circus party is the one I always come back to, because it is the most forgiving. Every child finds their station: the shy ones do face painting, the wild ones do the hopper ball race, and the big ones spend forty minutes falling off a slackline and loving it.
You need almost nothing that is actually circus. Red and white striped fabric does ninety percent of the work.
Tip
Make the rice filled balloon juggling balls with your child the week before, it takes ten minutes and they cost nothing. Keep the face painting station in the shade, and put a bowl of water and a cloth beside it for the child who changes their mind.