Necroposted (not by me), but I missed it before. Oh, I'm so glad that people read! I could cry.
My first thought was Stephen King's
The Dark Tower series - it's long, expansive (interesting locales! score one for background artists!) and has a pretty apt level of ridiculous throw-in-cool-shit bloat.
Then his self-insert and the self-insert dude from
Excel Saga could have a battle royale.
The "Family" stories by Ray Bradbury (Homecoming, Uncle Einar, The Traveler, and I forget whether there are any others). Partly because I think the author would hate it and tell everyone to go to hell, which is always entertaining. But like someone mentioned upthread about Lovecraft, a lot of the effect is in the narrative voice. But then, a good director can get that on film too.
Lovecraft, for me part of it is his concept that some things are so horrible as to be beyond the grasp of the human mind. I don't think that can be captured quite the same way on film. Still, maybe some of the smaller-scale stories would work, like the Innsmouth one and now I have to stop rifling through my bookshelf to see what it's called you know which one I mean yeah okay stop.
I hated
Ender's Game because I'm not a 15-year-old boy, but it is an absolutely PERFECT fit for a shounen anime. Good call.
Tad Williams'
Otherland might be fun - it would have to be either entirely in CG, or animated by a rotating set of directors a la
The Animatrix according to world. But it would be eighteen thousand hours long and nobody would finish the damn thing.
