"Nineteen Minutes" and "The Pact" by Jodi Picoult. After reading these, I definitely want to read more of her books.
Alice Hoffman is another writer I like - her novels are a bit quirky (and to me they seem to get "quirkier" the more she writes - her early ones were more straightforward, IMHO) but might be something you'd like.
Nora Roberts tends to lean toward the romance side, but she does have some that have more plot to them. She's also done some trilogy books that wander into the sci-fi realm (not anything like Dune or books like that) like the series that had the book "Morrigan's Cross" in it, and the one that had "The Hollow" in it (both of those trilogies have been completed, so you could read all three in a row instead of having to wait months for the followup installments to be published. I hate it when I have to wait.