How about some less well known metal?
Nightwish - actually mainstream in Finland, far from it in the US, definantly extremely good. They play power metal, it is more straight forward the progressive but tends to be more exciting. And the vocals! The singer is sooo good!
If you want to try something with an irish type sound try -
Skyclad - Metal with a fiddle and some folkish stuff, fairly unrefined, but good irish music is that way after all
. A quick song to check out is "Spinning Jenny", I love that stacatto singing along with the fairly simple but well played rythms, and the fiddle just adds to the fun
.
Black 47
Flogging Molly
In the vein of DT (I would consider DT mainstream, the song "Pull Me Under" appeared on MTV) -
Shadow Gallery - Softer, more vocals (Better vocals too), but some heavy fast stuff, good to excellent overall.
Royal Hunt - Heavier then DT, kind of like stratobvatius.
Tempest - more folky, some prog metal thrown in but more emphasis on the folk. Rather interesting stuff. They sound a bit like the 70s style prog groups too.