None of the three songs/bands you listed above growl, or are metal at all. You want something more like that?
Slipknot is certainly metal.
Staind was metal on their first two albums, but has veered more towards ballads on their last few albums.
Seether I would consider metal, or hard rock.
What we don't want is the typical Journey/Foreigner pop rock ballad.
Have you ever heard Vermillion Part 2...it is acoustic, but still has a metal vibe...if the words weren't so dark, it would be the perfect song for us.
If you look at the common thread across most of the bands we like...Shinedown, Stone Sour/Slipknot (since it is the same singer), Soundgarden etc...these are guys that can sing, but whose vocals aren't necessarily polished. We aren't looking for a metal sounding love song...we are looking for a love song with a metal vibe, by a band that typically doesn't aim for top 40 ballads.
I know you are supposed to pick a song that has meaning to the couple, but all of "our songs" are a bit creepy lyrics wise.
King's X - Goldilox (lyrics don't apply to a wedding much, though)
Did you see the song listing for their new album Ogre Tones...they re-recorded Goldilox...I hope the new album is good...their last 2 or 3 were kind of meh...but they are a great band to see live.