I think some children's books are for all ages. I like to give Kevan Atteberry's Ghost Cat to people who've lost a loved one.
I'm almost done reading Everything Sad is Untrue by Daniel Nayeri and it's going to remain in my heart a looooong time. Also laughed out loud--there's a reason some of us have so many food and poop stories. At first, the writing felt choppy and the author intrusion (dear reader) could be too much, but I'm so glad I kept reading because after a while it was just me and him face to face. It's so intimate. He's a good storyteller and I loved how we get a bit of history, mythology and real life all mixed it. The patchwork can be disconcerting at first, but I promise you it's a powerful book. I want to give it to every person I know.