Books with similar themes to those of Treasure Island?

I am going to be doing what appears to be a fairly lengthy research paper in my 10th grade English cl connecting three books to each other. The first book I read was Treasure Island. I read Holes for my second book and found it had very little in common with Treasure Island, so I will probably be reading two more books. Does anyone have any suggestions for books that do not necessarily have similar plot lines to Treasure Island but have similar thematic elements? The only two themes I could come up with were "coming of age" and "betrayal", but I would definitely be open to other themes. I have to find literary criticisms on the books I read, so I would prefer books that are either extremely popular or old enough that they have aculated a sufficient amount of criticisms over time. Also, because Treasure Island was very difficult to read because of the era in which it was written, it would be nice for my other two books to be a little easier to read (i.e. I don't want to read any Shakespeare). Two books I was considering reading were the Count of Monte Cristo and the Kite Runner.