Nice shading, thinner walls. Add a saw-tooth shadow or something to give more depth on starirs. Stairs are slightly less clear, but easier to create rooms with a 3D drawing tool. This seems like about as good as we can get with 3D, and still be clean and maximally functional. How about white walls, nobody has black walls in their rooms.
Stairs are pretty clear.
But we're getting closer. Mark still doesn't like black walls, wants brighter colors. Ah, some depth back, but almost the 3D again. Walls seem too thick and black. Architecture drawings tend to have white walls.