Hmm ... Well, though Benjamin Thomas' book isn't ...
footnoted (a controversial move), it's very deeply researched. He may have known more about his subject than anyone else in 1952, the year his work was published. But Thomas doesn't get mired in obscure facts. His book is so intimately written that by the time it ends, you'll feel Lincoln's assassination has deprived you not merely of a great President but of a friend.
If that doesn't fit your mood, pick up Holland's book. This is another 500-pager. Even if you're looking for a shorter read, don't be put off by it's length. It's well paced. And though you probably won't finish it feeling a deep connection to particular figure (other than perhaps Holland), your understanding of how Christianity shapes our society will likely have been deepened and it will almost certainly have been challenged (in constructive ways).