Cemeteries are always good for dark themed shoots :0
I once helped with a darker theme shoot in a church & outside, but should ask for permission from the church first :P
I think even in a field with a withered tree on the background or something or at a school really early in the morning if you do it just right - I always thought empty school hallways were creepy
Or a really good bet - is close to a construction site or something, Junkyard - or that one random empty lot that everyone likes to dump their stuff in.
Good luck! :D