I'd say the two biggest cheerleaders for 3D are Ridley Scott and Peter Jackson*, both of which have said before that they never want to make another film in 2D. In his latest videoblog, Jackson says that he'd also have shot his Lord of the Rings film in 3D if he had the option.
Big marketing pitch:
The people who have seen scenes of The Hobbit at 48 frames per second say that it's like the back of the cinema has had a hole cut out of it where the screen is and you're actually looking into the real world.
And more subtle marketing pitches abound, many of them very seductive.
It's a great video blog, I think. Accessible, fun and waving towards some nice ideas about stereo cinematography and shooting digitally. Jackson and co. do a great job with these.
*At least as far as film directors go.