[jimt]

I realize I'm a little late in posting this, but ...
The last couple of times we've gone to Disney, I've used the 17-70 for general shooting, 55-300 for for Animal Kingdom safari ride and a Sigma 10-20 for parades (if you can get close enough)
In the last year I've picked up the DA 21 and the DA 40, and will see how they work out.
Carrying the gear in a Lowepro Slingshot backpack, is really easy and the pack fits on all of the Disney rides. With the Slingshot you can spin it around in front of your body and use it as a lense changing bag/shelf as you walk.

Jim