Both Drew G. Faust's This Republic of Suffering and Annette Gordon-Reeds's The Hemingses of Monticello: An American Family are finalists for the 2008 National Book Award. I read and reviewed Faust's book and am about half-way through Gordon-Reed's book. Both are worthy finalists and I highly recommend them to you.
My money is on Faust.
Faust’s book is so good that I was actually sorry when I finished it because I wanted to keep reading….