You could do a princess and knight theme. Princess wands for the girls, foam swords for the boys. There are tons of ideas online for a party like this and it could be really cute.
Or since you have a bounce house make it an Activity Party. Ya know something like "Games, Games Games".
You could get some pillow cases or potato sacks and have a sack race.
3 legged race.
Get a whole bunch of crazy adult clothes, have the kids get in 2 teams, split those 2 teams and put half at each end of a row and then have the kids race down to their box 1 at a time, put on all the clothes in the box, race back to the other kids on their team and take all the clothes off and then the next person has to put everything on. The winning team is the one who finishes dressing and undressing everyone and put the clothes back on the box. Its fun to add crazy clothes long sleeved shirts, skirts, floppy hats, scarfs, lots of items though. Its a ton of fun.
They have plastic trophies and gold medals at Factory Card Outlet to pass out as party favors.
You could pretty easily make a gold medal cake and have your daughters name written in the gold medal part. Take a 9 inch round cake pan for the medal part and a 9x13 pan with the cake cut down the middle and placed at the topin a V shape could be the ribbon part.
Ok, I will shut up now. I love planning parties, once I start talking I can't stop!
Have fun!!!