Not to be picky (sorry!) but Skara Brae is a much much earlier neolithic settlement, not iron age. You're right that it's still definitely worth a look as they did like round buildings though they tended to be of drystone construction rather than sticks an' mud. =P

Speaking of that region, the small settlements centered around brochs are also worth taking a look at. Some of them were very interesting fortified settlements but again, the "maps" you tend to find are pretty small. I always loved brochs though.