The Alchemist by Paulo Coelho
The writing style is simple, but everything is a metaphor. Even the plot is a metaphor. It's not a difficult book, especially if you are the philosophical sort who often ponders the meaning of life.
The Metamorphosis by Franz Kafka
Surreal, weird, disorienting. Also quite slow. You need patience both for following the story AND understanding the meaning of the plot. Also, be warned that it's a mind-eff. If you're familiar with the literary term "Kafkaesque", this is its origin.
Not all those who wander are lost.