They do make a paint for glazed tile and grout but I've only read about it and can't say if it works.
I like the rug/carpet idea. You can get this flat, rubber backed indoor/outdoor commercial looking carpet for just a few bucks a yard at the home center. Lay it out and cut to fit with a knife. I put some down in the RV. Have put carpet down in an unfinished basement (no pad, no stretching on tack strips, etc., just something to walk on and keep the tootsies warm). Easier than paint, easier to pull back up, and last I checked, kilz and other paint gets awful expensive. Then paint will chip when all the kids start dancing at the party and it will get tracked through the house. The baby will crawl on the floor and lick it and so will the animals. Any moisture under the floor(there probably is some), and it will peel like a banana. Lay a 3' square piece of plastic or a piece of foil on the floor and tape it down all the way around the perimeter with duct tape. If you find moisture after a few days, then your paint won't last long but it may wait for a rainy spell.
Other than that, its your party, your floor, and your money. Talk to them at Sherwin Williams and see what kind of recommendation and guarantee they would give you. Check out the carpet but I have tender and cold feet so I'm partial to carpet. Good luck.