Fairy tales and mythology offer a solution to this problem.
In European lore kingdoms of elves and fairies were often times found in tiny forests. In Shropshire, among other places, for example, any small batch of trees could could contain a fairy kingdom. Most ordinary humans walking through these small batches of trees wouldn't run into the fairies or elves, or even know that there was a kingdom which stretched for miles contained within them.
The fairy and elven kingdoms in these woods were in a magical dimension which could only be reached under specific conditions, such as walking counter clockwise around a certain tree or hill.
Shropshire, like many places with rich fairy histories doesn't have vast wildernesses. Yet there are stories about people who get lost in these small batches of trees, finding themselves in an extensive fairy land. Indeed one of Shropshire's most famous kings would negotiate deals with fairy kingdoms that existed in tiny batches of forest.
For your game
What this means is that massive fairy, elf, and other similar kingdoms could exist within your human kingdom. An extensive set of nations, hundreds of miles across could be wedged magically within a city park no more than a few hundred feed across.
Doing this can allow you to make a simple human map, while putting elf and fairy kingdoms down as landmarks that you can build upon separately.
As part of Eldritch Earth
Obviously this idea is perfect for Eldritch Earth (Urban Fantasy World we're developing)
Another interesting notion is that of fairy paths. Indo-European cultures from Ireland to Pakistan had a notion that fairies had to travel along certain paths. These paths could be what amounts to magical tunnels from one pocket dimension to another.
Images of Shropshire...
|The largest forest in Shropshire is Wyre Forest, which is about 23 Kilometers in area...|
images are from http://www.geograph.org.uk/photo/1384615