At that resolution, I don't think pixel art can provide any aesthetic benefits. It will take a long time to draw using this fine level of control, but the results will be too small to appreciate.
I think you should re-read this.
Looking at your last version, with the dithering and all, the building is very monotonous. You should add A LOT of details, to make it come to life.
I know it's in an early stage, but maybe it would be better to have a building not proportional to the characters.
