Well going down the line and remembering stories that hooked me:
GL: The first soap to have me hooked and the story was Maureen's death and her aftermath. And Roger/Blake/Holly's family dynamic drew me in too. Chaotic yet good.
Y&R: Keesha's AIDS story
B&B: The Sheila saga
ATWT: Damien/Holden/Lily 1.0
AW: Iris shooting Carl (thanks to Evan Frame)
DAYS: I think the story was the coronation
OLTL: I think the beginnings of Jessica and Antonio I think. I saw them and rooted for them even though I liked Keri too. And I floved them till the end.
AMC: The Proteus story. Many people hated it but I loved it. Loved Vanessa Cortlandt too.
GH: GQ and Journey. Yes, I liked Journey and Kung Fu Barbie. Plus, she was my Alli Fowler, so. . .
And GQ was (and still is) my fave GH couple. D*mn Lulu's sleazy a** to h*ll for ruining them, and Guza for killing Georgie! 
British Soaps
Eastenders: Who Killed Archie
Corrie: The Tram Crash/Anniversary episodes
Emmerdale: Around the time Tom Wylde was murdered
Going off what I had, some form of good murder mystery, or sweep stunts will bring in new viewers; I'm a firm believer too that stories that a pulled from the headlines that are scandalous gets people tuned in; however, endearing character during those stories is what's gonna keep them in the long haul. At least that's what happened with me. . .
Edited by Nothin'ButAttitude, 21 February 2013 - 11:08 PM.