After reading The Devil in the White City by Erik Larson, I'm convinced that there isn't a bit of Americana that didn't orginate or pass through the 1892 Chicago World's Fair. It's a non-fiction book, but because it follows the creation and execution of the Fair itself as well as a string of serial murders that took place at the same time, it reads like fiction. Larson does a great job of bringing the time period alive on the page (which inspired me to Google photos from the Fair itself), and anyone who enjoys history will love this book.
The title and the premise of this book seem sacriligious, but Christopher Moore's Lamb: The Gospel According to Biff, Christ's Childhood Pal is very well researched. Moore himself takes the trouble to, in the afterword, explain his motives and approach. The book is a look at the first thirty or so (unchronicled) years of the life of Jesus. Naturally, there's a lot of humor involved--Christopher Moore has become known for that. His humor is an acquired taste, and I highly recommend that you acquire it as soon as possible (two of my other favorites are Bloodsucking Fiends and A Dirty Job). The big irony here is that my brother, a Christian pastor, would find this book hilarious--but he's so busy at the church that he can't find time to read it.
Timeline is one of my favorite books of all time, for a number of reasons. First, Michael Crichton knows what he's doing when it comes to period pieces; this fiction book has a four page, two-section bibliography on Medieval France (where most of the book takes place) and Quantum Physics (which is how the modern-day protagonists get there). Second, this book's chapters are titled simply by a countdown, which helps to build the suspense of an already fast-paced adventure; in short, this book sucks you in and won't let go. Finally, this was the book I loaned to my fiancee on our first date; since we're getting married three years to the day that I loaned her this book, my copy will probably never leave my library again.