[Apollonian]

I'll second the random element. I also like exploration in my games, so I lean heavily on random generation; this procedure lets me be surprised with the results. "Why does this dungeon have two groups of white apes?" That provokes my creative impulse into coming up with answers for discordant results. I feel free to tweak results to come up with something for players to have fun with, but I get a much more satisfying result off of random or semi-random input than I do from making it up whole cloth.

The other thing I do is research; I generally try to "start with earth" for my campaigns, and so I end up doing a lot of exploring in that sense; I now know much more than I ever expected to know about medieval Switzerland as a result of a short campaign a few years ago, for example.