I do like me a good melancholy tune. Excessively sentimental styles/lyrics seriously put me off (and it's rare that I find music which strikes a balance), but songs with wistful tones are, to me, very powerful.
I really dig Pink Floyd and Radiohead, but generally I don't listen to bands which primarily produce songs focused around negative emotion.
I can't decide which of the two DT songs I've been listening to lately to post, so here's the one about the pain of creative block (not knowing how to start on a project)