I for one enjoy diversity in games. Im not saying games that take place within 1 area(such as black mesa in half life) make the game bad, but diversity can improve things. Work the diversity around the time-period which the story/game/whatever takes place around. Trying combinations of things also increases the players interest in diversity. For example, a mushroom forest is always interesting. Or perhaps a cave filled with luminescent crystals is more to your liking. The possibilities are truly endless. I also believe that the proportions also matter. If the game/story will have a relatively small map, don't make a city take up half of it(unless the main setting just so happens to be the city). Lastly, unique landmarks are important as well. If your world has 3 forests, make sure they have differences. Perhaps one forest will contain a cave with untold treasures, while the next forest is far north and has perpetually snowy weather. Diversity is what makes a good map, in my opinion.