Ever since Cirque du Soleil burst on to the International scene, circuses have been so much more than elephants and traditional clowns. And costuming is where a true sense of the alternative can be conveyed.
For Very Young Children
Children can love a circus but it can also scare them witless. For children who are 10-years-old and under, think about the kinds of things they are learning in school and experiencing at home and in their world. Then pick a theme. Little kids will respond to a group of people costumed with some sort of cohesiveness. For instance, try animals. Keep it to domestic animals that they may find in their neighborhoods like cats and dogs and rabbits and birds. You can keep the body costumes simple using leotards and simple things like tails and paws, but make the faces the focal point. Paint on friendly, cheerful expressions and get long floppy ears, whiskers and noses. Or go for a flower theme, making everyone's head the center of the flowers and have multi-colored petals and leaves. Above all, go for friendly and familiar.
For the Family
Expand out from what you'd wear for just small children. Parents and older kids need entertainment too. But there's no need to get too slinky or sophisticated, perhaps embarrassing teenagers with their parents. But you can show a little leg and cleavage here and there. Again, themes are best. Think of using birds as your costuming theme. Some clowns could be large goofy birds with huge heads and big feet, while aerialists and equestrians can be in slim fitting leotards with painted on feathers and beautiful headdresses. Or choose a theme like Fairy Tales. Again there is room for oversize and friendly characters like ogres and trolls, as well as gorgeous princesses and princes. A wicked step-sister clown or a ringmaster dressed as Merlin would also be good ideas to work around. Renaissance Fairs' traditional garb would translate very well to a circus. Think kings and queens and serving wenches as well as princes on horseback and fair maidens on the high wire.
Adult Circuses
Again, this is an area pioneered by Cirque du Soleil. Adding an adult sense of humor and a liberal sparkling of sexual sophistication is a new area for circuses. And costuming really has diversity in this genre. Think Cabaret-style of Berlin in the 1930s with motorcycle caps and leather suspenders with very little else. Again, animals are a good theme, but spice it up with form-fitting costumes that convey a sensuality like leopards, tigers and cougar big cats. The slinkier and a little kinkier the better. Think about using long luscious hair extensions on the ladies and muscle T's for the men. You could do a 1950s American theme with Marilyn doubles and Elvis impersonators. Or go for Vegas-style headdresses and Vargas pin-ups. The main thing is a little more skin, lots of style and everything showing the bodies of the great athletes that circuses employ.