For stairs below floor 7, use the one which doesn't show underneathe and the one you have used; use for above floor 7 areas.
Personally i don't like those sprites; as well as they don't fit there. It seems you are making an evo/high rate exp? And therefore that doesn't matter so much.
However if you keep the green/turquoise walls, please make that wooden/nordic wall the same inside.
I would personally use another floor type, maybe cobblestone? And make small nature parts coming off the buildings for the bushes and trees.
TIP *when you use grass, only use the 2 smallest sizes.*
And make all water and landmasses, random. Since "mother nature" has designed them and they need to be ridged, shapish etc.
Good luck