I improved the pixel-tileset a bit more. It's still a fair distance from complete, but here's a much better idea of how a good minimap should look.
Here are some new screens of my progress so far:
Before and after 1: Layer above river. (Before: Spring of 51, Just arrived at embark)
1:
2:
Before and After 2: +1z above the front gate of the fort. (After: Autumn of 55, post-siege, and successful defense.)
NOTE: Varied Ground is still active in both images; for consistency.
Reason the trees are highlighted is due to the seasonal difference. However, you should easily be able to spot the farms and the backbone of my drop-bridge system (since we're above it in that image; It's a better way to showcase the land difference between z-levels). Obviously, darker land is below us, lighter land is current layer. I haven't adjusted the tree-top blocks yet, so they still stick out like sore thumbs.
My next work, since I got the text part knocked out of the way, is going to be making the world map easier to interpret all kinds of extra and some shared characters, and then extra items in the tileset. And then one final adjustment to the main fort/adventure mode portions of the set that may no longer look right post-processing of the prior.
Once I'm done overall, then it should make an excellent frame of reference for anyone willing to tackle the minimap idea, and it's extra features.