@octofish - I agree partly - Number of the Beast... would make a terrible movie. Like most of Heinlein's later books, it's WAY too talky. I enjoy that in a book sometimes, but for a movie - no way.
I think Glory Road could be well done, though. Yeah, a lot of talking again, but most of it isn't integral to the plot, and the Quest for the Egg could be a lot of fun. The Igli sequence by itself could be worth the price of admission.
Of course, this leaves me wondering if removing all of the discussion from the books is why none of the movies made from Heinlein's work have been any good - and yes, I'm specifically thinking of Starship Troopers.