There are a LOT of possibilities here:
The Adventures of Mark Twain – You can still find this in the “Children’s” section of video stores, but it’s not a kid’s movie. It’s a Will Vinton masterpiece done in “Claymation” (which is a copyrighted or trademarked term for Vinton’s process, not a genereic term). Everyone is (deservedly) making a big deal over Aardman studio’s work with “Wallace and Grommit” and “Chicken Run”, but the earlier work of Will Vinton is virtually ignored – and was pretty much ignored even when it first came out. This feature film is a case in point. It combines all or parts of “The Celebrated Jumping From of Calaveras County”, “Captain Stormfield’s Visit to Heaven”, “The Mysterious Stranger”, “The Diary of Adam and Eve”, and other Mark Twain books, combined in a framing story where Tom Sawyer, Huckleberry Finn, and Becky stow away aboard Mark Twain’s balloon, which is riding to a rendezvous with Halley’s Comet. The animation is gorgeous and witty, and at times even moving. I’m a BIG fan of Twain, and of animation, and I hate to see this one so neglected.
Creator – I’ve mentioned this one frequently on the SDMB. Jeremy Leven’s screenplay, based on his novel. It’s the story of a Nobel Laureate in biology (Peter O’Toole) who is trying to clone his dead wife. For a change, a movie about cloning that’s not stupid. This one is literate and witty, with one heck of a supporting cast – Vincent Spano, Virginia Madsen, Mariel Hemingway, David Ogden Stiers. Science Fiction with no special effects. The only movie I’ve seen where grad school looks and feels like the real thing.
** Panic in the Year Zero** – early 1960s black and white film about a family’s attempt to survive the aftermath of a nuclear attack on Los Angeles. Concentrates on their solving problems to survive (How do you cross a highway filled with cars going OUT, and who have no intention of ever stopping to let you through?) Stars Ray Milland. It FEELS like good Heinlein, but has nothing to do with him.
** The Last of Sheila ** – Another one I’ve often mentioned on the SDMB. A murder mystery that gives you all the clues – but you still won’t get the answer. A beautifully layered mystery with interesting characters. Again, a good cast – James Coburn, Raquel Welch, Dian Cannon, Richard Benjamin, James Mason. Directed by Herbert Ross. Closing song by the not yet well-known Bette Midler. Screenplay by Stephen Sondheim (yes, the composer/songwriter) and Anthony Perkins (Yep, Norman Bates himself) !!! This film is the half-brother of Sleuth (which I also recommend), which was suppposedly inspired by Anthony Schaeffer’s visit to Stepher Sondheim’s game-filled apartment. TLOS, like Sleuth, features a group of people caught up in the machinations of a wealthy games-player, who especially likes setting up elaborate mind games and revenge.