I have been known to describe Agalloch's music as The Unforgettable Fire on metal. They play a sprawling, atmospheric style, drawn from black and folk metal. John Haughm has one of the most comprehensible rasps I've ever heard, and his clean vocals are very good too.
My other favourite metal band, who also do the variation between harsh and clean vocals, is Orphaned Land. Alas, nothing on Sordo. But their album Mabool is a milestone in metal. I can't say I ever expected a metal song to feature a passage from the Torah as its sole lyrics, followed by a beautiful piano outro, but it happens on that album.
Also, I'm going to e-mail you a song by Opeth, Bleak. The first 3.5 minutes are flat-out death metal with Mikael Akerfeldt's death growls, but then the middle section features beautiful clean harmonies between Akerfeldt and, yes, Steven Wilson. SW produced the entire album it's on, and that production job in turn influenced In Absentia.