I am going to take a page from my friend Brian over at Remote Synthesis and recommend an album/song for everyone to try out. The music I have selected may not be exactly mainstream, but I think if you listen to it you might just like it.

Tristania is a heavy metal band that combines full orchestra's, a choir singing in Latin, female operatic voices, and heavy guitar rifts. The music is dark, but at the same time it sounds very angelic. I don't much like how heavy metal has gone these days with all of the growling or screaming that they do on the albums, but this one is tolerable. I really enjoy their use of the choir's that sing in Latin throughout the songs, it sounds really cool.

For an introduction to Tristania you could try going over to Pandora.com and listening to the music there for free. You can try to create a station there for "Tristania" or the songs "Deadlocked" and "World of Glass". If that fails you can get the previews of songs off Amazon:

Tristania - World of Glass