If you are anticipating being in any situations where you may get wet (Aladdin's spitting camels, for instance, or a splash fountain) you may want to prefer using lightweight woven clothing that day. (This goes for the grownups as well.) Remember that woven fabrics dry more quickly than knits of the same weight, are more comfortable when damp, and tend not to get that "dragged down" look.
Another good trick to do is to carry a flat cloth diaper (or washcloth) in your bag for cleanups, along with a little bottle of dishwashing liquid, or my personal fave, Wal-Mart's antibacterial hand soap, which is the best universal stain remover I've ever used! Paper towels are useless for scrubbing at spills on clothing, they shred. Besides, a flat cloth diaper is thin, very absorbent and big enough to use as an emergency bib, cover-up or cooling cloth.