I still haven't managed to edit the pictures I took at the Harry Potter studio tour - iPhone 4 combined with fairly low lighting levels means they need s bit of tweaking - but I did play with some on Instagram. I applied the same filter to them all and thought the results were quite atmospheric.
The great hall, which was built as a permanent set, apart from the roof which is just a studio roof. All the magical ceiling effects were superimposed using a scale model of the roof and carefully synchronised camera angles.
Harry Potter's dormitory
The potions classroom
Dolores Umbridge's study
Mrs Weasley's clock at the Burrow. I so need one of these clocks that displays the whereabouts and well-being of all family members. Either that or one of those war time maps which showed the location of army units.
Ollivander's wand shop
The scale model of Hogwarts Castle used for flying sequences and other magical stuff. The lighting goes through a full 24 cycle every few minutes so you can see the castle as it would look at all times of the day and night.
For anyone in the UK I would highly recommend the tour. The detail of the sets is stunning, and it was fascinating to see how the whole thing was put together from initial concept art to the finished films.