I just finished reading Thomas Merton's Seven Storey Mountain. This is a very different book from anything else I've read by him, and I certainly would not recommend this as a starting point. Not that it's not good (it is very good), but unless you are already familiar with Merton's work and thought, what he's contributed to the literary canon of meditation on the spiritual life, you might find yourself wondering why you should care about the life he is writing about in this autobiography. This is one of the first books he wrote after joining the monestary, and its early origin is evident to someone more familiar with his later work. The most obvious example of this, to me, was the way he talked about other faiths and denomonations within Christendom. He has very little respect for the "opposing" denomonations, taking what come across as cheap-shots at their "erroneous" ways of understanding and practicing the faith, and speaks of Catholocism with an almost idolatrous reverence.
There is a great 10-minute biography of Merton's life here