First and foremost, I would like the Harry Potter movies to be REMADE. I saw the first, hated it, saw the second, and resolved to not waste any more of my time and money watching that turd
Next, I think George RR Martin's song of ice and fire would make an excellent (albeit very long) movie series. The depth of his characters is fantastic, and it would make a great epic fantasy if done right.
Finally, I'd like to see something by Rohinton Mistry made into a movie. The interaction and dialog in his books are superb, in my opinion.