My favorite of the series is The Silver Chair, with The Voyage of the Dawn Treader as a close second. Other ones I enjoy include The Magician's Nephew and The Lion, the Witch, and the Wardrobe. But really, they're all terrific.
About The Silver Chair from goodreads.com : Eustace and Jill escape from bullies at school through a strange door in the wall, which, for once, is unlocked. It leads to the open moor ... or does it? Once again Aslan has a task for the children, and Narnia needs them. Through dangers untold and caverns deep and dark, they pursue the quest that brings them face to face with the evil Witch. She must be defeated if Prince Rillian is to be saved.
About The Voyage of the Dawn Treader from goodreads.com : The Dawn Treader is the first ship Narnia has seen in centuries. King Caspian has built it for his first voyage to find the seven lords, good men who his evil uncle Miraz banished when usurped the throne. The journey takes Edmund, Lucy, their cousin Eustace, and Caspian to the Eastern Islands, beyond the Silver Sea, toward Aslan's Country at the End of the World.
The chronological order of the books is as follows:
- The Magician's Nephew
- The Lion, the Witch, and the Wardrobe
- The Horse and His Boy
- Prince Caspian
- The Voyage of the Dawn Treader
- The Silver Chair
- The Last Battle
However, this isn't nearly all that Jack Lewis wrote! He also penned The Space Trilogy which I haven't read yet, The Great Divorce, Screwtape Letters, and Until We Have Faces.
Finally, while this is technically just a book post, I've gotta point out that the Focus on the Family Narnia dramatizations are amazing. They follow the books closely, and bring them to life. Utterly awesome. Definitely something you want to check into!