I'm listening to Nightwish right now! If you guys like Nightwish you'll also like Epica, Beyond The Black and Battle Beast.
I really love this genre of metal a lot, I've been getting into a lot more symphonic metal and progressive metal in the last few years. I still love old school thrash (Metallica, Slayer, Testament, Megadeth, Anthrax) however I'm blown away by the sheer talent that a lot of the newer metal bands have, especially when they incorporate more instruments than just your typical guitar, bass and drums, and when the singing is way more melodic (I'm not a big fan of metal bands with "Cookie Monster" lead singers!).
Speaking of progressive metal, the last couple of years I've really gotten into the German band Vanden Plas. I actually like them a lot more than Dream Theater (who I've seen in concert 4 times now) As a side note, the lead singer of Vanden Plas (Andy Kuntz) added me as a Facebook friend last year after I commented on their page so much (that was a total geek moment for me!) He's a car guy too, he's got a McLaren 765LT (which just so happens to be my favorite car!)