Those are my three favorite Vonnegut novels. Nice choices :-)

I'd second my sibling poster's recommendation of Galapagos, if you haven't read that one.

Slaughterhouse Five and Cat's Cradle are probably his two most widely-read and widely-referenced books, so if you haven't read those yet and you're still on a Vonnegut kick after those three, maybe read them. They're all quick cotton-candy reads anyway, so it's a small cost to read another. I do consider Cat's Cradle overrated, though. I think all the cute and memorable made-up words have boosted it to higher prominence than it deserves.

I recently finished Galápagos and was blown away. A story about how a few people unknowingly manage to escape humanity's demise by getting stranded on the Galápagos Islands, and their descendents' subsequent evolution over the next million years, all told from the perspective of a ghost... CLASSIC Vonnegut.