1.) A Connecticut Yankee in King Arthur’s Court – there have been an awful lot of movies that were "suggested by this book, and several nominal adaptations. Not one of them is at all close to Twain’s story, and not one captures his wit, style, or mood. The two biggest adaptations were simply Star Vehicles (for Will Rogers and Bing Crosby, each portraying hero Hank Morgan essentially as themselves).
I suspect too many filmmakers were scared off by the idea that they’d be offending the Catholics. But I maintain that you can make a film of this that captures much of the book without doing so. Not one version has shown us The Destruction of Merlin’s Tower, or The Fountain of Holiness, or Hank Morgan’s Quest. There were moments of real emotion in the book, as well – such as the King’s encounter in the smallpox hut. And nobody tries to show Hank Morgan’s own limitations. Worst of all, no one ever seems to treat what’s actually funny in Twain’s book.
2.) From the Earth to the Moon – the only real adaptation of this book was a joke, not at all faithful to verne’s novel. This would make an interesting “steampunk” sorta thing, as Disney’s 20,000 Leagues Under the Sea arguably gave a push toward steampunk in the first place.
3.) i, Robot – the Will Smith film started out as a story completely independent of Asimov’s book, aside from being based on the Three Laws. Changing the names of a few characters in a story and then saying that you’ve filmed “I, Robot” is like making a couple of characters in The Red Badge of Courage female and saying that you’ve filmed Gone With the Wind.
I’d like to see this redone with CGI and Harlan Ellison’s script – that had the blessing of Asimov himself, and a good Citizen Kane-derived structure.
4.) The Time Machine – maybe one of these days they’ll get it right. George Pal loved the book, but he wasn’t really committed to putting Wells on the screen – how many viewers really understood what the Morlocks were, or understood the implications? The remake a few years ago threw out the book almost completely. With modern CGI some of the scenes could be awesome – the decaying Museum, the giant crabs at The End of the World.
5.) Doc Savage – I think I heard that they were doing this, in fact. One hopes they’re doing it right. Properly handled, it could be great adventure. Certainly, badly handled it could be, well, as bad as the first film version.
6.) The Case of Charles Dexter Ward – this has been filmed at least twice. It’s arguably one of Lovecraft’s more accessible stories (alongside The Shadow over Innsmouth*, see below), but hasn’t been done justice. This could be Great.
7.) the Shadow over Innsmouth – filmed more than once, but the recent Dagon was a bloody disappointment. This is a film that really needs CGI. And it’s Lovecraft at his most action-oriented. ,