If I may suggest, I think it's be neat if a Floating Mountains biome of some sort, similar to the ones in Avatar. I've always thought the glitches in the Extreme Hills generation was cool, but a biome made specifically for it would be fantastic.
EDIT: Also, another thought, in the Deadlands, I think it'd be cool if it were lightly raining ash particles. Give it a more of that feel that it's going for. I can't find the right word for it.