I never read any of those books save "The Grapes of Wrath" by Steinbeck. I know a fair bit of it.
First off, the book is interspersed with narrative chapters and so-called intercalary chapters explaining the Joads situation in a more universal perspective. The Joads are a migrant family from Oklahoma during the problems of the 30's in the Dust Bowl (U.S.). They are tractored off their land and have to make west towards California, "the land of promise." During their travels (as it is a "journeys" theme novel) all the character grow both spiritually, emotionally and physically. Those that can't adapt die off (such as the grandparents). Not a pleasant ending, but a realistic account of the situation as it was happening, a characteristic feature of Steinbeck. Another interesting feature of his narrative style is his colloquial use of swear-words such as "shit" and "damn" and "bastard" and whatnot.
That should start you off as a little teaser
