I've got to admit, Elemental seems to bring out the need for traditional classical music in me, but at the same time, due to the very intense aspects of a post apocalyptic word, bent on mutual destruction through magical warfare, or the potential of survival and growth in a world gone wrong... Apocalyptica stands out as a personal favorite for me. Four Cellos, fusing together the heaviest basses, and most complex guitar solos typically only found in Progressive Black Metal albums, with an elegance and sound typically only found in Classical Music. A mix of the classic, and the gritty. It's pure, refined Symphonic Metal, to go with a game that in itself is a mixture of the classics of Civilization, with the gritty, unrefined yet progressive feel of Master of Magic. It's the perfect metaphor for Elemental. To me, it's the perfect music to play while dominating the post-cataclysmic world of your choice and creation.
So, here's the next ten songs on my playlist. Note it's in random order, hence the embarrassing presence of some songs. 
(I'm also more of a ska, thrash or metalcore guy, so I'm not as well versed as the rest of you in true Metal, so forgive me if I'm neglecting your favorite mind-exploding band in my playlist.)
What's yours, and why?