My best suggestions for young boy readers, say 8-12'ish, is John Flanagan's Ranger Apprentice Series. It's fabulous! I got it for my son but I was the one on the thrill ride. It's about the life of an orphan, Will, and his friends. It is set in a Robin Hood like time period, with swords, mystery, and a twist no one saw coming. I was so eager to get this series, I ordered them all. I have since passed them out, doubting I ever have the series complete again! ha!
My best shape shifter series for teens is Shiver and Linger by . Her last book in this trilogy comes out in June, I believe. It's called Forever. I enjoyed this series as Grace discovers the true identity of the wolf, Sam, that has spent his life watching her. Its a beautiful first love experience. In Linger, the story continues with a role reversal and potential heart break that will have you literally screaming NO! at the end of the book.