I've long loved The Muppet's Treasure Island. I was happily surprised with the extra bits of adventure found in the actual classic story. When I got to the 25% complete mark in the book and they had already arrived at the island, I wondered what was left. Well, lots!
I've read that Treasure Island is a book wherein Jim, the main character, encounters various characters and from his encounters must decide what he'll be like when he grows up. Yes, I suppose. I didn't see his decision points, as it doesn't seem that he talks through them much. But there are very different characters with very different values. Some are misjudged at first and lead to betrayal, others to unexpected respect.
A great book of adventure.