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I lived about 10 minutes from Disney for about 15 years... And had the chance to visit many many times. I have no experience with the 16-85 (maybe someday), but the range seems perfect for Disney. I would not worry about a long telephoto as much. For most of the parks, that range will be enough.
Looking back over my last shots at Disney World, the only spot I see where a telephoto might really be a must is at Animal Kingdom. I have the 55-300, and it's like molasses to find focus, but the shots are nice. But, even there, I would make do with a shorter lens just fine.
Good luck, and enjoy your trip.