When it comes to designing a game setting I've always wondered how much to put in one area. How many dungeons should be a days ride from The Constipated Hobbit Inn? How many ancient alien complexes should be a short jump away from that Class K space station? There seen to be different approaches to question, with some gamers cramming lots of hot-spots into a map, with others spreading them out over a larger area.
The former style is clearly at work in the late Dave Hargrave's legendary (notorious?) Arduin campaign setting. Take a look at this map from one of the grimoires and you'll see that despite being just a small corner of the world it's bursting with dungeons.
In fact, all of the published Arduin dungeons are on that map. They're all within spitting distance of one another. A somewhat similar approach is evident in Jeff Rients' excellent comedic Encounter Critical module, Asteroid 1618. Jeff mapped out the Vanth sub-sector of space Traveller fashion. Along with the planet Vanth it includes Gamma (Gamma World), the spaceship Warden (Metamorphosis Alpha), Orezius (Uresia), Mythika (Mazes & Minotaurs) and more.
Even given that this is something of a tongue-in-cheek game, that's a lot of adventure locales in one small sub-sector.
The other approach is the one taken by the Judge's Guild in their classic Wilderlands of High Fantasy setting. This involved maps covering near-continental swaths of land and the dungeons and adventure modules that were published to tie into it were spread out over vast distances. A similar approach seems to be evident in Christopher B.'s Dark World, where you have a large area mapped out where the dungeons will be spread around.
So which approach do you use? Do you put all the interesting thing within easy reach of each other? Do you disperse them, placing them far apart and setting the stage for epic voyages?