I read a post some time ago about hand sanitizer on this board... it said that Purell type sanitizers do nothing to prevent certain illnesses (I think the poster was actually talking about rotovirus or norwalk), but that Wet-Ones do kill those germs. So, we use wet-ones after every other ride usually. And it feels good to be wiping everything off our hands, and then throwing away the wipe, rather then rubbing something into our hands...
Anyhow, that's our plan, wet-ones often, and a good hand washing after each potty break (which with a 5 year old, is about every 2 hours.)
I also bring travel sized lysol with me, and zap the hotel room remote (which is the dirtiest thing in a hotel room), head-board, phones, toilet, sink handles, door knobs and light switches--as soon as we arrive.
And (yes, I am a little germaphobic), I also bring a baggie with clorox wipes for on the airplane, and do the airplane trays, arm rests, seatbelt clips, and knobs above our head, as well as around the window where dd sits.
With all of this, we don't get sick when we are on vacation. We also make sure we eat pretty well, and drink lots of fluids.