Though nothing can compare to reading the classics of literature for yourself and forming your own opinions of them, it is always nice to get the perspective of others. Here are some books that I have found very helpful in giving overviews of different works as well as introducing me to new authors.
Invitation to the Classics by Louise Cowan and Os Guinness
This is probably one of the most helpful books on western literature that I have read. It covers just about everything from the ancient to the modern classics including novels (Dickens, Tolstoy, Flaubert), political woks (Machiavelli, Rousseau, de Tocqueville), religious & philosophical works (Luther, Kierkegaard, Aquinas) and poetry (Eliot, Keats, Shakespeare). The book, which has a Christian perspective, moves in chronological order and summarizes each work including plots, themes and author bios. At the end of each summary, there are then questions to ask yourself regarding the themes of the work as well as recommended editions and translations. It is a beautiful book with selected quotes, pictures and trivia as well as sections on classics from different countries including France, Germany and Spain. It was through this work that I was inspired to read many of my favorite works including The Brothers Karamazov, Madame Bovary and Les Miserables. If you don't read any other reference book on great literature, read this one!
The Well-Educated Mind by Susan Wise Bauer
This is the companion book to Bauer's The Well-Trained Mind, and its main goal is to help train your mind to the format of a classical education. In the 1st half of the book, Bauer focuses on reading and re-reading and re-reading the works as well as EXTENSIVE note taking. The whole thing is rather daunting and would be very time-consuming if you were to follow it to a "t", but thankfully, you can take certain elements and use it in your reading. The 2nd half of the book contains helpful summaries of different works including fiction, non-fiction and poetry. Though you may not want to implement Bauer's whole plan, it is certainly worth a look and you will probably find many helpful tips for your reading.