Anne McCaffrey has written tons of books that would make great movies, but I don't think Pern would be one of them. I think viewers would shoot down a flick in which 99% of the time people are nice to each other, even with the menace of thread. They'd have to destroy the story to make it 'hollywood'.
The Planet Pirates is one of my favorite sci-fi books written by her, and would make a great film (you should read this if you think yourself a sci-fi fan). The Acorna series, about a little unicorn-like girl found in space, could be a Disney film, and I bet kids and adults would love it.
Ben Bova has written many great sci-fi books, that are perfect for films. Character studies within science fiction settings; get some great actors and these could be a huge hit. Take the Mars books; an American Indian scientist fighting for Mars exploration, while the world tries to shut it down, after they find ruins on Mars.
But, without a doubt in my mind, the sci-fi book that should be made into a movie is Neuromancer.