Getting back into the swing of blogging, I've been going back through my posts about hex-mapping. Part 5, where I discuss placing the terrain features that exist between mountains and coastline, brought to mind a conversation I had with a friend about alternatives to pseudo-realistic geography.
The guidelines I gave will tend to generate a landscape that is reasonably realistic. This should give you a map suitable for a campaign built around the assumptions that under-gird the stories of Conan, Elric, Fafhrd and the Grey Mouser, or Odysseus. In short, it's designed to fit very well with what most of us consider the default assumptions of the early versions of D&D.
Good 'ol Appendix N has a lot more going on in it than just those stories. Consider the landscape of the Arthurian romances, for instance: trackless forests peppered with magical castles, enchanted pools, and bridges fashioned from giant swords. The lands of Narnia and Oz are like unto it. All of them share a moral component in their landscapes. The moral character of the land's rulers and inhabitants actively shapes the landscape.
In Part 5 of this series, geography informs the location of populations within it. A more Arthurian geography turns that on its head. The twisted and wicked troll king does not choose to live in lands of tangled brambles and sulfurous hot springs. Rather, whatever land the troll king chooses to dwell in will eventually become tangled with thorny brambles and dotted with sulfurous hot springs. Likewise, the lands around Camelot are not rich and fertile due to geography so much as the virtuous nature of the King and his court ("The land and the king are one.") Should that virtue be compromised, the land's fertility will suffer and fair weather will turn foul.
If that's more the feel you're going for, you should place your terrain features after you've decided who lives where. Kingdoms will tend to be small (most seemed to have but one large city, if that many, and it was centered around the capital castle) and there will be little trade between them. It wouldn't be unusual at all to come across some land or castle nobody from back home had ever heard of before. You might even easily cross between worlds without realizing it, a la the Mabinogian.
It doesn't need to be an either-or thing, of course. Tolkien's Middle Earth seems to borrow a bit from column A and a bit from column B here, where the geography itself is anthropomorphized enough to create its own moral atmosphere. Ancient tragedies create modern terrain hazards, but most of the world appears to operate under the forces of geology and meteorology well known to most of us. In such a world, the features of the troll king's kingdom have a certain chicken-or-the-egg mystery about them; does he live there because he chooses, does the landscape follow him, or does he create it somehow?