Personally... I think where hi-def disc formats really stand out in video are in movies with wide shots particularly of scenery. Movies that take place in smaller settings with a lot of tight shots aren't excercising the format.
That said... my absolute favourite BD collection for demonstrating what it's capable of is Planet Earth the complete BBC series Blu-ray collection.
From the opening scene showing the sun peaking out of one side of the Earth is just brilliant. It looks so real to me that when I view it in a dark room I get a dizzy sensation.
The rest of the series is full of shots that are 'that good' although not all. The whole thing is filmed in hi-def but the shots range from a little grainy to spectactular. There are lots of amazing panoramic shots in this - easily the best I've ever seen.
Many shots are taken from planes or helicopters showing you natures marvels like the
Angel Falls in Venezuela.
The episode with that scene takes your POV down the river and over the falls - if you have a really big 1080P set I don't recommend this be viewed by the elderly or people with heart conditions.
Some older movies that are restored nicely look very good also. I am very impressed with Blade Runner and the Dirty Harry series which I am going to do a review for. Fox and Warner releases are consistently good quality even the older movies they restore. One problem with older films is that they often descend into graininess when the scene is darker, perhaps someone knowlegable about film can say why.
So... rule of thumb for me is - true classic films I love with lots of outdoor scenes and wide shots I might consider upgrading the disc from DVD to BD. But if it's mainly a character driven story with lots of dialogue I wouldn't bother.