Of Mice and Men - John Steinbeck

Of Mice and Men is sort of "Grapes of Wrath Light". It holds a lot of the same themes, but is a lot shorter and has a more colorful cast of characters. You can read the thing in an afternoon, and even though it's not as thematically dense as Grapes of Wrath, it's a lot more efficient in saying what it wants to say. Really hard to go wrong here.