I love your image of Eleanor belly-laughing at The Backward Day. One of the joys of reading with kids is the surprises they can hand you.
I think it's always useful to remember that small children have -- and should be encouraged to have -- very eclectic taste. Eleanor can be captivated by a delightfully silly story like Chickens to the Rescue, then listen in fascination to The Wizard of Oz. Just like grownups, kids enjoy many different forms of writing.
A few additions to your hilarious list:
Backward Day is a New York Review of Books reprint of an out of print classic: they've been exhuming both novels and picture books from earlier eras. This month they released a delightful one: Russell and Lillian Hoban's
The Sorely Trying Day. It's from the folks who wrote Bread and Jam for Frances and sequels, and it has that same sense of families being loving but chaotic and sometimes contentious, always with a large dose of humor. Father comes home from a Sorely Trying Day, only to discover that the children are squabbling miserably. An investigation ensues, with each wrongdoer pointing to a wrong that was previously done to them. Once that circle is closed, a new circle of apology ensues, with everyone trying to outdo the contrition of the previous apologizer. It's just really funny.
Then there's Robert Munsch, best known for The Paper Bag Princess, but he's written dozens of books. He was a pre-school teacher, and his humor is very slapstick. One of my fondest memories of picture book hilarity is of watching my spouse's loving but somewhat taciturn father reading Munsch's
Thomas' Snowsuit to Mona when she was probably around 3 or 4. Thomas doesn't want to put on his snowsuit, and ends up in a series of confrontations (visuals: cloud of dust with hands and feet occasionally poking out) with various adults. When the dust clears, it's always the adult who's wearing Thomas' snowsuit. Mona started giggling, then laughing, then her grandfather started laughing, and he ended up stopping reading and laughing uncontrollably. The power of Munsch.
I'll toss in Katie Davis's
Who Hops here, which appears to be a much younger book. But there's something about it that appeals to many 3 and 4 year-olds' sense of the absurd. "Who hops?/Frogs hop./Rabbits hop./Kangaroos hop./Cows hop." (picture of very startled purple cow, who on the next page thinks, "It would never work.") And it goes on from there.
A quick note on Ruth Krauss, author of The Backward Day. She also wrote the great
A Hole is to Dig, illustrated in 1952 by the young Maurice Sendak. It's sweet and offbeat -- not hilarious, although it has its smiling moments. It's a series of definitions which aren't really, like "A hole is to dig," or "A hand is to hold." Her "a face is so you can make faces" attracted a little flack from critics, who felt Ms. Krauss was encouraging rude behavior. Ah, the Fifties.