Yeah, I think a decent rule of thumb is to think whether or not the map is effective at conveying what it is supposed to represent, rather than the actual supposed relative size in real life. Keeping it at the most size-efficient layout and making sure that it still allows non-cluttered movement routes should do the trick.
@Mirku:
I really like the tileset style in that one. Can't help but feel that the head of the sprite seems to be squashed, though. D: Kind of reminds me of a lego guy actually, hahah.
@006:
That's pretty sweet, love the style. The angles of the buildings kind of throw me off a bit though, as they don't seem to be 90 degrees angled relative to eachother like how building blocks usually are. Not really a big deal at all though, since it kind of gives it an unique perspective.