Two top contenders from her list of SF that's really fantasy:
The Stand, by Stephen King, and The Passage, by Justin CroninRead about another entry on the list.
They're basically the same book, except King's is more lively and weird than Cronin's. A plague hits the Earth that kills most people - in Cronin's novel (the first in a trilogy), the remaining people are turned into A) "vampires" who are compelled to obey the commands of a psychotic killer who is basically patient zero, and B) nice small town folk who begin to hear, psychically, the voice of a perfectly good little girl, who cannot age and remains in a state of innocence and love. It's the classic good vs. evil scenario, and the psychic powers feel more spiritual than scientific. In The Stand, the remaining humans are divided between those who hear the voice of a devil-esque guy in Vegas and a Jesus-esque lady on a nice farm. Both books depict a scientifically plausible end-of-world-via-disease scenario. And both go off into the realm of impossible fantasy and spirituality when they set up their good vs. evil plot structures.