Sure thing! Here's a few works that kind of showcase what I mean while still clicking with the stylistic choices you've presented:
(by Faxdoc)
http://waneella.tumblr.com/ really, anything this guy does is also a good study. He does a ton of intricate sceneries and designs that fit with what I'm tugging at!
The big thing I'm trying to get across I guess is imbuing character to your landscapes. Think about purposes for the areas, is it a market place? factory district? some kind of religious area?
You gotta work small details into the world, hint at some kind of story. Plain landscapes are well and good, but don't hold interest as well as those more thought out details.
Of the works you've posted, only the post-apoc picture really has any palpable character to it. But there's still more you coulda put in there like hints as to why things are so goofed in the scene, or why the person's sitting there.
As an example of what I mean, if I'd done the scene I would have had a dead soldier or something leaning in just off-screen, implying a fight for why the person's all bloodied up. Some supplies maybe, something they died defending. Smoke plumes in the distance, implying what's happened is still happening, or some plantlife/decay to imply it's been long-done.
Small details like that breathe SO MUCH visual interest into a picture!
If you want non-pixel art examples to look at, ghost in the shell (both the live-action adaptation and the original anime series) do wonderful jobs of this with their set designs.
