Currently: Flaubert's Parrot, Julian Barnes. (I'm into it, but it's taking a lot of brain power to read some parts.)
In the past year:
Anna Karenina, Leo Tolstoy. (2nd time, love it, much easier read than War & Peace)
The Blue Flower, Penelope Fitzgerald. (strange & beautiful, didn't finish because of MCATs)
Ragtime, EL Doctorow. (loved it)
The Secret History, Donna Tartt. (lost interest after the murder, which you learn about on the 1st page, didn't finish)
some short stories by Alice Munro (they are brilliant, but I can only read one at a time), Ellen Gilchrist, and Angela Carter (love her stuff).
My favorites: Love in the Time of Cholera (Marquez), Howard's End (EM Forster), The Periodic Table (Primo Levi), Wide Sargasso Sea (Jean Rhys), everything by Flannery O'Connor.
Other writers I would recommend: Lorrie Moore, Bernard Malamud, William Trevor, Jonathan Franzen, Shirley Hazzard (esp The Transit of Venus)