dont let the sheer weight of them there riffs consume you. theyll make you nauseous.
attention deficit - the idiot king. great song writing, playing, and variety from this trio. and you might swear on your mother's grave that there's keyboards, but the band assures you that your ears are being deceived by guitar manipulation.
the esseness project. even better song writing and playing (and also largely devoid of keyboards). i could go on and on about the compositional brilliance. accessibly complex with dynamics mostly unrivalled in the instrumental world. theres times when you'll find three distinct bass parts. im not talkin bout layering. you'll get a driving bass riff, with a seperate bass melody, as another bass part solos over top. and while all thats going on, youll also get a seperate guitar melody and possibly an atmospheric guitar part. i would say check out It's all In Your Mind if you can find it; they kinda run the gamut on that one.
in the past year ive also gotten into estradasphere quite a bit. avantegarde instrumental isht. youll get anything and everything from those guys.
some other favorite have already been mentioned, like blotted science, morglbl, and animals as leaders. morglbl remind me of a more experimental version of OHM. i know you aint lookin for jazz fusion type stuff, but their album Circus Of Sound is most excellent.
and im sure you know of liquid tension experiment. and jordan rudess solo material.
and dear gawd, i hope youre aware of mr. vai.