Absolutely LOVE sonata arctica.  That and TSO are the only bands I have gone to see in concert. I got an album and t-shirt signed by the whole SA band.  My dad (who got me into SA) and I went to see them about 2 years ago in Atlanta.  You know, they toured sometimes with Stratovarius right?  Finnish Metal For the win!  For those new to SA, try listening to the album End of This Chapter.  The majority of my favorite songs by SA are on it, so that is a good place to start, IMO.  "Don't Say a Word" and "Fullmoon" are my favorite songs, though I love almost all of them.  

Another good Power Metal band is Freedom Call.  I used to play their music nonstop when I was playing KOTOR and KOTOR2 on the Xbox.