When looking for an area to establish a town find wide open plains or a massive mountain. These two map elements are very good but are not the only thing to look for.
Mountains can be used as the support frame or 'Skeleton' of your structure. Digging to make rooms is a lot quicker and economical with very short travel times. If you wait on replacing dirt walls and floors with something else makes for a quick start up.
On open plains you'll need to build a tight formation or a single multiple zone house. Its all about going up once you are safe with 2 high walls with a roof overhead.