Back in primary school the knuckle method that we were taught seemed too complex and slow, so I made up a word instead from the 30-day months: "apjuseno".
I would dispute at least "The Name of the Rose", I'd say it's just a multi layered story.
A good portion of the book are philosophical discussions, which would be IMHO very boring and not understandable for small children.
The magic of novels like Svejk or Little Prince is that those extra layers are mostly implied, emergent, they're not written out explicitly and thus don't bore out the young readers.
This one is a little difficult: the book is laden with multilingual dialogue and notes apparatus; it's not for everybody. That said, I first read The Name of the Rose when I was 11 or 12, and I thoroughly enjoyed it.
Personal anecdote - I rather enjoyed reading "Name of the rose" as a kid. I don't remember how old I was at the time, maybe somewhere around 11-13. While I obviously didn't understand a lot of the details at the time, I remember vaguely feeling that there was something deeper than just a murder plot. All in all, it was a pretty good experience, and served as my gateway drug into other books by Eco.
I have to disagree, there's plenty to do and see in Pisa. While it can't compete with Florence, right next to the leaning tower the cathedral and the baptistery contain some of the earliest examples of renaissance sculpture, and the sinopia museum gives insight into the technology of fresco painting. There are also several other museums and churches scattered around the city center and the riverbank, worth to pop in even if you're just trying to escape the summer heat.
And as others mentioned, its airport and train station make it a convenient hub to explore the surrounding area, including Calci, Lucca, Cinque Terre, and Livorno.
https://www.youtube.com/watch?v=LknkrGnCTG8