Blind Guardian, awesome band, saw them live recently
try:
Nightfall in Middle Earth
Night at the Opera (very symphonic, the name says it all)
Somewhere far Beyond
those are my favorite
also check out Demons and Wizards, it's Hansi Kursch from BG and Jon Schaffer from Iced Earth
for Opeth try Blackwater Park and their new one, Deliverance
To improve technique and of course trying to keep all as clean as possible. I know my own limits and speed limits and so on I never play anything I'm not capable of. That wouldn't make any sense. After three years of playing I tried to play everything as fast as possible and that sounded, I would say, like shit, and I didn't realize that if I'd play bit slower things than I was capable of playing then everything would sound much better.
--Aleksi Laiho - Advice to Play By
