As mentioned above most people live in Cotui (closest good size town). It's not a really large town, but good size enough that you'd get a mid size supermarket and other amenities such as the largest man made lake in the Caribbean - Good for picnics, exercising, fishing, etc.)...and if you can't find what you need there you can always go to San Francisco de Macoris which is a much larger town with at least a Walmart sized store (La Sirena).
Piedra Blanca is not a bad option if you don't mind living in a small town, but it's a little bit farther commute than Cotui. Housing in Cotui BTW has gotten a lot more expensive since BG came to town as there's now a bit of a housing shortage. Still not as expensive as other larger towns. BG has their own transportation from Cotui to the mine (I see hundreds of people every morning waiting for their buses to come by). In terms of cooler parts of the country you're not going to find much of that unless you live up in the mountains (Jarabacoa, Constanza, etc)...
PM me for more info if you decide on Cotui.