Dash & Lily's Book of Dares was, I think, the third book co-written by David Levithan and Rachel Cohn, but it was the first I read; I picked it up because a bunch of people recommended it for a Christmas books thing I was writing. It's a good one for when your Christmas feelings are a little mixed - especially because of the way the point of view alternates between the two characters. Lily's always been pretty into Christmas, Dash hasn't, and this year they're both at loose ends. I liked this way better than I expected, because at first I feared that Lily would be a manic pixie dream girl, but she's not, and that's practically the point. There's some bonus awesome bookstore stuff, a lot of humor, and a nice dash - hah, I crack myself up - of romance. I'll definitely be returning to this one in Christmas seasons to come.
(Disclaimer: I know David a little from working together at a conference, but he in no way asked for this review, blah blah.)