Love this band, no idea where the original poster got the Taylor Swift comparisons from! I also love Nightwish, Theatre Of Tragedy, Lacuna Coil, Within Temptation, Evanescence(though I REALLY wish Amy would get around to recording a new album, it's been 5 years now!) and "In This Moment"
I like Halestorm (though it baffles me how many people from their home state hate them). I found their live EP at Nuggets for $2 many years ago and thought it was pretty solid. Odd to release a live EP as your first major-label offering, but I guess given their current popularity it didn't hurt. Hale's voice is bad-ass, too. Maybe not Ann Wilson bad-ass, but probably too different to even compare. She's great, though.
And Shawn, have your wife check out these bands:
And this may be too symphonic, but if she digs Heart, Lana Lane is a dead-ringer for Ann Wilson.