I've got another book recommendation for you. The Faith of America's Presidents by Daniel J. Mount is a book you really ought to have on your bookshelf. It was published in 2007, so the first president in the chapters that work their way backward in time is George W. Bush. The chapters are mostly short, ranging from three to over twenty pages, depending upon the president and his spiritual beliefs. There are extensive bibliographies at the close of each chapter as well.
I found this book fascinating, and it is one that I will return to again and again. It's easy to pluck it off the shelf and read about just one man who led our nation (although most often reading one will lead to two and then three).
My current series is set at the same time WWI was raging in Europe, so I was quite interested in reading about Taft and Wilson, our presidents leading up to and including that time period. I believe it gives me some insight into the times so that I can make life even more realistic for my characters.