Bit overkill with links there, might want to trim it down a bit otherwise no one will listen to any of them (:
In answer to your thread: sad, subtle music. Trance does fall into this category with certain songs, it's not music that tries to shove its one gimmick in your face. My favourite genres for this cover IDM, classical, post-rock, ambient and indie. I'll put an example for each.
IDM: Boards of Canada - Dayvan Cowboy
Warning: Spoiler!
Classical: Gustav Holst - Jupiter
Warning: Spoiler!
Post-rock: Sigur Ros - Untitled 1
Warning: Spoiler!
Ambient: Aphex Twin - Rhubarb
Warning: Spoiler!
Indie: The National - Sorrow
Warning: Spoiler!
I'm some what of a fanatic about this kind of music, don't think I can quite describe how emotionally dependent on it I've become ):