I guess it goes under the category of hard rock, but Joe Satriani's music is mostly instrumental.
I have "Flying in a blue dream" (which includes vocals) and "The extremist" (all instrumental). The latter is the best of those two in my opinion, but "Flying..." has the best song, "The forgotten (part two)", but "War" from "The extremist" is almost as good.
I heard some of his earlier stuff, but it wasn't as good as those two, although it was okay. I heard some from the record with the white cover where he holds a silver guitar and it was good too!
I also recommend Satyricon's "Transcendental requiem of slaves". Not what Satyricon usually does, as it's pretty slow and weird, but it's great.