I just finished writing a huge paper on Mormon polygamy from a feminist persepective and I needed to write a section about church history. I had a really hard time with it and it was hard to divide the pro from the anti which was difficult. One book which is an older one that I used and thought was good and uncritical were these ones: (they are in citation form as I copied and pasted them from my bibliography)
Bushman, Richard. Joseph Smith and the Beginnings of Mormonism. Chicago: University of Illinois Press, 1984.
Daynes, Kathryn. More Wives than One: Transformation of the Mormon Marriage System. Chicago: University of Illinois Press, 2001.
Eliason, Eric. Mormons and Mormonism. Chicago: University of Chicago Press, 2001.