Mo Willems doesn't need any promotional help from the likes of me, but we just read Knuffle Bunny: A Cautionary Tale for the first time, and oh! We both like it so much. I find it more personable than the Pigeon books, although of course I love them too. There's so much to act out here, and Jackson loves it when I say "Aggle flaggle klabble" and "snerp" and doing the "Trixie bawled" and "Trixie went boneless" parts. By the time we read it a second time, he was mumbling "Knuffle...knuffle" as I turned the first page. And I'm pretty sure if I were to take him into a laundromat in the near future he would immediately know what it is.
Runner-Up: When I Was Young in the Mountains by Cynthia Rylant, illustrated by Diana Goode, was an impulse grab this week, based on the feeling I'd seen it recommended somewhere on the Well-Trained Mind forums, and it's lovely. We've been reading Tikki Tikki Tembo as part of an extension of China Week, wherein of course the two brothers fall down a well, and Jackson immediately recognized the word when it came up in this very different book! When I Was Young in the Mountains seems like it ought to be for older and/or more sophisticated kids, but somehow the images and the language really connected with the kiddo.