Yes, Thanks for the tips, everyone! I knew something about moleskin, but I didn't know you could buy it here, I thought it was an American thing. I'll be picking some up at Shopper's next time I'm in, along with the Earplanes for the flight.
As it happens, I have a brand new, inexpensive (Giant Tiger) knapsack that I bought a few months ago to have as a spare for when those damnedable nylon zippers break on the kids' backpacks, so I will get some scotchguard and give it a whirl. I had planned on bringing in a few bottles of Dasani each day to the parks, but I can see how buying the Brita's will save on lugging around a knapsack full of water bottles all day, I'll have a look for those as well. My DH and I each have fannypacks with the bottle holder attached so I won't need any holders. I will still have to buy some water, because I'm going to bring some packets of sugar free kool-aid to mix with the water sometimes for a treat for the kids, and it will probably gunk up the filter in the Brita's.