brent
For sure, Grapes is very heavy, but so is the subject. Personally I will never forget it, and I think about it often, particularly the end scene, the turtle, and the man at the campfire who talked about watching his family starve. "The Red Pony" pony is another one that falls in that category for me. I find that Steinbeck either wants to have a good time and celebrate life (Cannery Row), or he wants to punch you in the gut -- but the punch in the gut is usually for a good reason that you come around to later.
Never heard of Wayward Bus! I recently rented some short fiction of his and really enjoyed "The Pastures of Heaven," a series of interconnected stories about different people who are doomed by their contact with a certain family. The family isn't really evil, just the harbinger for bad things to come. Great read, if a bit morbid/sad. But it's Steinbeck, so it comes with the territory.