Lens for Disney World trip - Long

The advantage of the 18-200 is its range. It isn't the sharpest lens around - but having said that, I've taken a lot of pictures with it that I think are excellent as far as sharpness is concerned. Using it with my D7000 I took a lot of night pictures on a trip to Turkey and Italy last year and was very happy with the results. But the D7000 can be bumped up to a very high ISO level and still give good results. Not sure about your camera.

If by stock pictures you mean the ones taken by the Disney photographers - they always seem very good. My son gets them since he doesn't like to use a still camera when he travels with his kids - just the movie camera. Of course, they will be the same pictures thousands of other people have - just with your family in them. But after all, that's what we want with family pictures.