I don't mean to come off as a wise ass, but I'd like to mention the books and authors that I know of, that I enjoyed the most, in the different languages I have had the chance to read them.
English: Ulysses by James Joyce, a master piece that used the structure of the Homeric Odyssey as a contrast to the lives of the Dublin working class. I love the way the author manages the time throughout the plot, but above all I like his frank realism, especially crude for the days when the book was written.
Spanish: Too many great authors. But any book or short story by Jose Luis Borges. This author's perspective of life is so realistic, that it seems to be oniric.
German: Faust by Goethe. Although Schilling is a great writer too.
Italian: struggling with "Il Principe", by Niccolo Machivelli and "Baudolino" by Umberto Eco. I've read both books in other languages, but I'm trying to read (and understand most of it) in Italian.
Just my .02