I get why you'd include him in the "having a laugh" group, but I don't really get that from Vonnegut, overall. The most-uplifting I usually find him is on par with Camus' "Myth of Sisyphus", so a kind of dark, existentialist sort of uplifting. Even most of his "jokes" are a pretty big downer when you think about it, and much of the time he's not telling jokes at all (Mother Night or Deadeye Dick or Galapagos or Bluebeard have humorous and absurd parts, but I'd not characterize the overall effect as funny or absurd, at all—the humor's so you come away with "well, that's life" and not "Jesus, I guess I should go kill myself")