Strangely, with Vai's work, I don't miss the vocals as much. His sound, his approach, he's a lot more "un-rock" than Satriani and his compositions are that way too. Vai to me is more like a keyboard player and that is not knocking him, he's one hell of an instrumentalist and has a recognizable sound all of his own.
In a rock setting, I would have loved to see him with Alcatrazz (where his techno & effects guitarship really worked). I did see him with Whitesnake in 1989/90 - man, I could have certainly done without that.
In comparison to him, even Vandenberg (not my favourite WS guitarist either) sounded as earthy as John Lee Hooker.
Now listening to mid-seventies live recordings of Chappo's Streetwalkers. Good band they were, the ole goat! They had a very special twin guitar sound, courtesy of Charlie Whitney and Bob Tench, something I haven't heard that way before (and as you might have gathered by now: I listen to a lot of twin guitar harmony music!
).
Just got the Steven Wilson Remix of Jethro Tull's Heavy Horses in, gotta give that a spin too.