For us, we've decided that we need to be around a fair number of university-educated people (or at least people who are able to think at that level - they don't have to have a degree). So, first, we need at least a town, not to live 40 miles from nowhere. And second, we need that town to be either a college town or the kind of town where people move there after college.
That's just us. You may be different.