I loathe Cat's Cradle, which I read last summer upon recommendation; thankfully it's a fast read too. The first half of Vonnegut's narrative is enticing, with the air of a good mockumentary, and, initially, the banana republic of San Lorenzo was the very image of my ideal guilty pleasure dream vacation destination. But about half way in, Vonnegut ruins the fine plot development by revealing the entire republic of San Lorenzo to be peopled by cynics and nihilists adhering to a "religion" which is little more than a philosophy of fate melded with crass impiety. Furthermore, Vonnegut strains a wacky and unintentional misuse of science to convey a sense of almost hyperbolical hopelessness which really let me down. So definitely avoid Cat's Cradle.
A larger tome to avoid is Joyce's Ulysses. Long before the painfully cynical, cryptic, and ofttimes just plain dull narrative's end, I realized that the epic existed for the sole purpose of displaying the author's mastery of divers styles of writing: fine, but mingling the lot of them was little more attractive than a dank mixture of all the colors of the rainbow. Not to mention that the characters are detestable and go unreproved for their pettiness.
A good alternative, combining the length of Ulysses and the threat of man's destruction human failure of Cat's Cradle, is David Foster Wallace's Infinite Jest.