If your into Demons and Wizards I take it your already into Blind Guardian and Iced Earth? Same with Luca and Rhapsody. Really, nothing beats Rhapsody for cheese.
Some other good bands based on what you mentioned might be Domine (Emperor of the Black Runes is a fantastic album), Helloween, Angra, Wuthering Heights, Dream Evil, Gamma Ray, Tad Morose, 3 Inches of Blood, Iron Saviour and of course, the mighty NINJA MAGIC!