No special access, just happen to be in the right place at the right time. I mean, I have an employee badge (third party employee-- seasonal at Blue Man Group), so I was able to waltz in ahead of the crowds during the Diagon Alley grand opening, so that was nice.
Other than that event, I don't think I've ever gone to the parks specifically for photos. I have a quadcopter, though, and have been thinking about flying over the Kongstruction (not directly over it, just sending the quadcopter up from across the street would be enough).
I think I just like getting photos that are difficult to find. As in, you can find a million photos of the dragon spewing fire all over Google images, but there aren't many out there that have the confetti flying around from the grand opening.
And thanks for the good words!