I've recently stumbled across a group or project called Ayreon, its an interesting mix. Each of its albums is a story, with the songs and music telling each part. They don't have any set singers or the like but it reminds me of Dream Theater, later year Pink Floyd as well as having campy 80's power/hair metal thrown in there as well as orchestral stuff and even folk.
As an example - 'Everybody dies' is VERY 80's hair metal, it sounds like its the theme song for the sequel to Flash Gordon
and in another album - 'Druids turn to stone' is massively different.
I'd recommend folks give them a listen, The Universal Migrator is a damn good album as is The Source.