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.