wow! This may well be the most subjective question yet asked herein. Others have given you their approaches, but there are many you could take. One might ask the bridgekeeper's question (MP allusion): "What is your quest?" Do you want to be able to grasp literary allusions? (read the 'classics') Do you want to be able to talk about current popular books with friends and colleagues? (see the NYTimes bestseller lists or equivalent) Do you want to be inspired? Laugh? Cry?

My approach is to just read anything and everything that falls into my path (you have to recognize the chaff, of course :). The last two books that I've read are:
- The Voyage of the Narwhal, a novel by Andrea Barrett
- The Soviet Tragedy, by Matin Malia

Not that I'm necessarily saying that you should run off and read these; I'm just trying to illustrate the point: "Be eclectic -- you'll have more fun!"

I could never choose 2 books to take to a desert island -- I'd drown trying to make a choice -- or list my 25/50/100/200... favorites. When I'm asked, I generally list some favorite writers, those that I have learned to trust with my time or those that I reread. In no particular order these include: John LeCarre, John Hassler, John McPhee, Gene Wolfe, Kate Wilhelm, Ursula LeGuin, Shelby Foote, Carl Hiaason, Thomas Pynchon, Joseph Campbell, Peter Matthiessen, Joyce, Hemingway, Heinlein, Elmore Leonard, Gabriel Garcia Marquez.... Well, you get the idea.