I highly recommend ‘Life of Pi’ by Yann Martel, but I read the end of it on a five hour train ride from Fort Worth to San Marcos, Texas, and the people next to me started being loud so I skimmed through the last few pages so I could find another seat. I've recently reread the last ten pages, and they're fairly graphic.
Still, the book maintained colorful animals and a charming sense of humor for two hundred pages that were sophisticated enough for adults and stimulating enough for preteens and young teenagers... until the end. Don't say I didn't warn you, I had nightmares.
Also, the beginning of the book shifted from regular font to italicized font; the regular font takes place in the past, which is in first person, and the italicized font is the present, which is in third person. It sounds complicated, it isn't.