In that case, Balance's Retreat should be an awesome location. Unfortunately without really high initial capital that area wouldn't provide nearly enough income or food to sustain any army to make use of the potentially high level walls that can be built there.
For R/Tville, the opposite seems to be the case in terms of defense as Bael said. Food is no problem, as R/Tville don't really consume much in terms of cities, being pretty small in comparison to most Dwi cities. The surroundings are woodlands or rurals, but those provide relatively low income compared to most other areas, much like BR area.
On the other hand, travel is pretty quick in that area. That also means monsters move faster though.
