I would make China Mieville's "The Scar" into a movie.
Larklight (Philip Reeve)
Murder on the Titania and also Wireless (both by Alex Acks)
My vote goes not to a novel, but a comic-book series: The Life and Times of Scrooge McDuck.
But with real people, not ducks.
It's a twelve-part biography of the world's richest duck by Keno Don Rosa, in which Scrooge is present at numerous historical events - from the heydays of the Mississippi steamboat to the Klondike Gold Rush - and meets many well-known personalities of the period, including John Jacob Astor, John D. Rockefeller and Theodore Roosevelt.
I recently started an annotations series about the comics for Never Was.
It would make a great adventure series!
Oh I would love to read those! Considering Marvel canned Moon-Girl and Devil Dinosaur, I am in the market for a new series. Is it just one book? Or literally 12?
Mind you, if they did a movie of that in the style of the New Ducktales, with David Tennant voicing Scrooge, I wouldn't object! It's really good!
@Hilde, The Lifes and Times of Scrooge McDuck is twelve parts. And then there are about two dozen more adventure comics by the same author, many of them inspired by ancient history and myths, like the Library of Alexandria and the treasure of King Croesus.
It would also be amazing to see a movie adaptation of Toby Frost's Space Captain Smith series!
My vote goes to Perdido Street Station and Boneshaker, two excellent steampunk novels.
Any of the Ministry of Peculiar Occurences novels will make for a hot film series. With the right casting, Books and Braun can be as popular as Luke and Leia.
Christ Wooding's Tales of Katy Jay series would make a great TV series.
A miniseries for The Difference Engine.
By the way, @kevin's article, "Steampunk Novels That Should Be Made Into Movies," is now available at Never Was as part of the archive of his old website, SteampunkBooks.net.