I wouldn't want to drag something the size and weight of a DSLR around those parks. If it were me my wife would bring the Fuji X10 and I would bring the Olympus OM-D E-M5.
The Fuji X10 is small and light and gives great results under almost all circumstances you will find in Orlando. Also, I put a big red soft-release on it so if I want to hand it to someone to take a shot of us I can just put it in EXR-Auto mode, tell them to hit the big red button, and get great results.
For the Olympus OM-D E-M5 I would either bring the 12-50 for general shooting (especially since I could use it to take shots with water splashing everywhere and not worry), and the 20 f/1.7 pancake for when I need a fast lens.
In your situation I would just use the S100 alone, or pick up some other light and good camera to go with it so the wife and yourself can both have one... Like the Fuji X10, Nikon V1+10-30 (most parks) and 30-110 (for Animal Kingdom), Sony NEX, or an M4/3rds. It is going to be some long, hot, and frustrating days, and the less excess stuff you have to carry the better off you will be, and even a 60d + 17-50 is a lot heavier and bulkier than a Compact or Mirrorless and just won't provide better-enough results to justify the trouble.
Some other advice.... Get a small backpack and put a few very cold, if not frozen, bottled waters and some snacks and energy bars in it each morning before you head for the park. Both Disney and Universal let you bring that kind of stuff in, and not having to leave a line because one of the kids gets hungry or thirsty is invaluable. Plus you will also spend less time in food lines trying to get drinks just to avoid dehydration. Instead you will only get in food lines when it is time for an actual meal, which is a huge time and money saver.
My other advice, which you probably can't use, but which I offer to everyone.... The last week of February, running into the first one or two week of March is probably the best time to go to Orlando. Schools generally have breaks centered around Presidents Day, the Equinox, and/or Easter, meaning just before or after this time. Few parents can justify taking their kids out of school right before or after a week long break, so almost nobody goes there at that time. It is also an uncommon time for breaks anywhere else in the world so foreign families with kids are fairly rare as well. Overall things are very slow at that time, making for very short lines for everything. Also the weather should be very good at that time, not as hot as summer, but with little chance of actually getting cold, and relatively little rain as well. So if you can arrange to go at that time of the year I can't recommend it enough...