Both Cat's Cradle and Slaughterhouse Five are two of the best novels of the 20th Century.
I find most of Vonnegut's work to be outstanding. In some of his later works he became very experimental. Bluebird is written as an autobiography of the main character, and Timequake which is semi-autobiographical blending a novel he was not happy with anecdotes about his life.
Both Cat's Cradle and Slaughterhouse Fife are two of the best novels of the 20th Century.