HEROES_are_BORING at 2011-01-15 18:14:22:
I would say pick and choose what you writing at. Extreme Measures sounds overstuffed. Inception and Black Swan are "mashups" but are very focused in what they're trying to do. Don't get too fancy.
I would also say that, along with hitting all the genre sweet spots, find ways in which your 2/3 genres interact and overlap. It's those moments, in which the scripts premises butt against each other, that will give your story that "original" twist that stands out.
Example that comes to mind: Inception. Heist movies have physical confrontations. Dream/cerebral movies have falling/reality warping moments. Put them together and you have Arthur's fantastic zero-g joust with the security personnel in the hotel hallway.