Vonnegut's fun, and any random Mark Twain is great (especially Huck Finn), but man do I love me some Umberto Eco. His novels establish themselves in the period of their setting and just drill down deep into the minutiae, so his books are great if that's your bag. The first I read was The Name Of The Rose, largely as a way to hate-fuck that awful, awful movie adaptation (don't watch it by the way, it's awful. And by "it" I mean Christian Slater.) I have no qualms recommending it, nor Foucault's Pendulum, which is like The Da Vinci Code for people not confused by fractions. The Island Of The Day Before is also a cracking read. I cannot speak to the merits of Baudolino, but it sits on my shelf, taunting me. He also has collected essays, which are fine for what they are. But the novels have the advantage that they are so damn long and dense you'll only need one book for the whole break.
As for me, I'm spending the holidays plowing through the Lemony Snicket cycle.