[@bluetommy2]http://awoiaf.westeros.org/index.php/Armies#North
The North region is large, but of course quite cold. So, not so densely populated...like northern parts of Canada.
B:

[@Dawnscroll]http://awoiaf.westeros.org/images/e/e7/Map_of_westeros.jpg
Here is the right map for you to glare at.
The Vale is pretty damned isolated as well, but quite safe.
I'm strangely coming to like all this love letter exchange between the Lords Paramount.