Hexcrawls and the WSG

The review of using Central Casting: Dungeons for terrain generation is the last of my hexcrawl reviews. But what about the Wilderness Survival Guide? Where does that fit in?

The systems I reviewed were all random terrain systems. The Wilderness Survival Guide, on the other hand, doesn't use any random terrain elements at all. It tells you about the terrain types and climate zones, then walks through developing a realistic Earth-like world map. Thus, it's not really useful for off-the-cuff generation of a map during play.

However, I'm currently rereading the WSG as prep for creating my own hexcrawl system. The question becomes "which realistic elements of terrain can be worked into a random system, and how?"