People to Meet
One of the things I loved about Planescape was the way it flipped the standard D&D tropes on their heads. It brought the politics of deities and demons to the fore, it existed outside of all the other settings and therefore all of the other settings were inherently contained by it.
One of the particular things I liked was the way it took away many of the familiar races such as Elves, Dwarves, Gnomes and Halflings, and replaced them with Bariaurs (Goat Centaurs), Tieflings (Demon-blooded), Aasimar (Angel-blooded), and plane touched humans. Those other races exist in Planescape, but they are entities of the material worlds, not so much lesser beings, but beings focused on the local affairs of their realms rather than the creatures of planar cosmopolitanism that the setting focuses on.
If I'm developing a vague setting with these landscape images, that's the kind of direction I'm thinking of heading. I've developed a few interesting settings over the years both here on the blg and in a few of my game designs elsewhere, this might be an opportunity to tie them all together with some gonzo awesomeness that has scope to tie into any other setting as well.