I think that I generate terrain that I am familiar with but its both great and a bit racy to try something else. I reckon that the majority of fantasy had a dollop of DnD backing it and that was definitely steeped in Tolkien which was based around Oxford (Middle England !). All the halflings, elves, and orcs came right out of that and you even get the feeling it was more 'Hobbit' than 'LotR'. I like to stay with that familiarity tho I did run a campaign once which was set in a jungle. I tried to run Deserts of Desolation module pack but I found it hard to expand on the terrain beyond what was written in it as I could think of nothing more to say about it. When playing its probably no less fun to go anywhere but to DM or write / map for I would say there is a certain comfort about going local.