I tend to offer more designs on a wand so that they are easier to hold for the children and so they can wave the around and play with them. If it is a birthday party, I always make sure that the birthday child has an extra special balloon to take home.
I let the children decide which balloon they would like creating, giving them suggestions if they get a little stuck or overwhelmed. I have a portfolio of over 100 designs that I know how to make quickly, including Elsa & Anna from frozen, olaf, spiderman, batman, captain america, superman, hulk, iron man, all princesses, peppa pig, hello kitty, minnie & mickey mouse, minions, ninja turtles, creeper, and lots and lots of balloon animals.
Children (and adults) love to watch the balloons being created before their eyes.