There's quite a lot out there, though you have to hunt for it. If you want an unprejudiced look at polygamy, you may have to leave the western, "christian" world, altogether. All sorts of possibilities open up then. Here's a list I typed up for my own purposes, awhile back. I've read many of these books, others are still on my "to do list." Some of these books are quite old, but should be available second hand. The full text of some is available online. Happy reading!
The Rebellion of Yale Marratt (novel) Robert H Rimmer. A young man rebels against his privileged upbringing. The story begins in 1930's New England--the same setting as The Great Gatsby. But Rimmer's tale unfolds very differently.
Six Records of a Floating Life. (Autobiography) Shen Fu. Classic chinese love story about a man who marries his childhood sweetheart. One of his friends is polygamous, so his wife decides that her husband should have a concubine too. He, however, points out that they can't really afford that.
Judge Dee Murder Mysteries. (Novels) Robert van Gulik. These are set in ancient China; Judge Dee is the investigating magistrate. In the stories set early in the judge's career, he has two wives, later in his career, three. The wives make an appearance in some of the stories. Of note are:
He Came with the Rain. A short story in Judge Dee at Work. Judge Dee takes a moment to appreciate his family relaxing in a courtyard, in this work. In another passage he contemplates taking on a third wife.
The Haunted Monastery. Judge Dee, his wives and servants, spend a stormy night in a Taoist monastery. He investigates some mysterious deaths there.
The Phantom of the Temple. Includes description of Judge Dee's three wives.
Haremlik: Some Pages from the Life of Turkish Women. (Autobiography) First published 1909. Demetra Vaka Brown. The author was a Greek Christian woman who grew up in Ottoman Turkey. She then moved to the USA. Some years later, she returned to look up old friends, only to find that they were now in polygamous marriages.
Polygynous Blessings: Musings of a Muslim Wife. (Autobiography/Religious) MizAzeez. A compilation of seven months of blog entries, on the author's life as a plural wife. www.lulu.com
Bombay Gardens (Novel) Jameela Siddiqi. Naranbhai is a Ugandan-Indian landlord, a big man with a big personality, and two wives. His story begins when two strangers, who share a childhood fairtale, meet thirty years after the Asian Expulsion. www.lulu.com
The Lonely Polygamist (Novel) Brady Udall. The story of a polygamous Mormon man.
Polygamous Families in Contemporary Society. (Sociological study) Irwin Altman & Joseph Ginat. Classic study of a polygamous Mormon community.
Voices In Harmony: Contemporary Women Celebrate Plural Marriage. (Sociology/ Religion)Mary Batchelor, Marianne Watson, Anne Wilde. 100 Mormon women write movingly about their experiences as plural wives.
The Aryan Christ: The Secret Life of Carl Jung (Biography) Richard Noll. The author looks at the great psychologist's life. Carl Jung was not only in favour of polygamy, but practised it too, says Noll.
La Femme de Mon Mari (My Husband's Wife) (Anthropology) Sylvie Fauzang, Odile Journet. A study by two french anthropologists of polygamous marriage in West Africa, and amoung African immigrants in France. French language.
Our Kind of Polygamy. (Sociology/Marriage) David G. Maillu The Kenyan author describes how polygamy functions in traditional African society, and the challenge posed by ideas imported from the West.
142 Strand: A Radical Address in Victorian London. (Biography) Rosemary Ashton. John Chapman published a radical magazine, from his address in the Strand, London--The Westminster Review. As well as a wife, he also had a live-in mistress. When young Marian Evans joined them as his secretary, she fell in love with her boss. And that's when things started to get complicated. Marian Evans later on published novels, under the pseudonym Geroge Eliot.
Polygamy, Bigamy, and Human Rights Law. (History/Law) Samuel Chapman. Begins in the 17th century, when a debate on Christian polygamy was sparked off, by the publication of the King James Bible. The study continues to the present day, and the challenges facing the law today. http://www.samchapman.talktalk.net/PBHRText.pdf
The Perception of Polygamy in Early Modern England. (Religion/ History) Lisa Shirley Loughead. This paper argues that monogamy-only was adopted as a boundary marker, more than for theological reasons. It enabled people in the "civilised" world to distinguish the Christian world from the rest. Published by Dalhousie University
Mr Peay's Horses: The Federal Response to Mormon Polygamy. 1854--1887. (Law) Mary K Campbell. A ninteenth century legal case involving a man charged with polygamy. Yale Journal of Law and Feminism.
Jesus, Mary and Child. (Religion) Janet Tyson. The author argues that Jesus was married to two women, and Lazarus (not Peter) was his heir.
Polygamy: Tips to Succeed with Many Wives. (Marital advice) Puspo Wardoyo. The author owns a chain of chicken restaurants, and is founder of the Indonesian National Polygamy Society. Published in Indonesia; however, excerpts in English were published in Harper's magazine, 2005
Dreams from my Father. (Autobiography/Family history) President Obama writes about his polygamous father, who is a member of the Kenyan Luo tribe.
West African Folktales. Jack Berry. A collection of folktales from West Africa, some of them featuring polygamous characters.
Travels in the Interior of Africa. (Travel/anthropology) Mungo Park. Classic work, from the early nineteenth century, and still in print. http://www.gutenberg.org/ebooks/5266 also:
Floyd on Africa. (Cookery/Travel) Keith Floyd. An account of the TV chef's culinary tour of Africa. Some mentions of polygamy, in the South African section.
Arabian Flavours: Recipes and Tales of Arab Life. (Cookbook)Salah Jamal. Includes an amusing tale: "Mulukhiek: Green Leaves and the Startling Tale of the Octogenerian Emir."
Mencius. (Moral philosophy/ dialogues) Mencius was a Chinese philosopher of the Confucian school. The book named after him is a collection of dialogues in which he participated. Note:
* Book I: part 2:chapter 5 A dialogue with King Hsuan of Chi, who loved wealth and women.
* " V: part 1:chapters 1--5 Mencius and his disciples discuss the story of Shun, a legendary king.
* " IV: part 2:chapter 33 A cautionary tale of a man who liked to brag to his wife and concubine about the people he knew.
Lieh Tzu (philosophy/mysticism) Translated by A.C.Graham. Lieh Tzu belonged to the Taoist school, which used amusing stories to make serious points. Note: Towards the end of Chapter Two, a story about an innkeeper, who had two concubines, one beautiful, one ugly. (This story is not included in the older Lionel Giles translation.)
Papillion (Autobiography) Henri Charriere. The book which inspired the movie, starring Steve McQueen and Dustin Hoffman. When Papillion escaped from Devil's Island, he made it to Venezuela, where he lived with Indians for a time. The chief gave him his two daughters as wives.
After Polygamy Was Made a Sin. (History/ Religion) John Cairncross. Classic study of Christian polygamy nin Western Europe.
Sahara (Travel) Michael Palin. The book to accompany the TV series. Michael visits many West African countries touched on by the Sahara, and meets many remarkable people.
Travels in Circassia, Krim Tartary, etc. (Travel) Edmund Spencer. 19th century travelogue, which gives great insight into the patriarchal cultures of that region, and time.
http://www.circassianworld.com/new/history/miscelleneous/1240-travels-in... (Also see Google Books)
Romance of a Harem (Autobiography) Clarence Forestier-Walker. The author's father was sent by the French government on a mission to the Sultan of Turkey. She describes her experiences there, including her insights into harem life. Nineteenth century. http://www.onread.com/book/romance-of-a-harem-translatede-by-clarence-fo... OR http://www.archive.org/stream/romanceofharemtr00londiala#page/n11/mode/2up
The Romance of the Harem. Anna Leonowens. This book was the inspiration for The King and I. An Englishwoman is employed as a governess by the King of Thailand. http://books.google.com/books?id=qTxqEFrmOpcC&source=gbs_book_other_vers...
The Romance of the Harem. Miss Pardoe (Julia) Publ 1839 A collection of tales told by "professional storytellers in the harems of wealthy Turks in times of festivity." http://books.google.com/books?id=CgQnAAAAMAAJ&pg=RA1-PA174&dq=The+romanc...
The City of the Sultan, and Domestic manners of the Turks in 1836 Miss Pardoe. Available from www.GeneralBooks.com
Three In Love. Barbara Foster, Michael & Letha Hadady. Menages a Trois throughout history.
Polygamy in Islam (Religion. morals/marriage) Abu Ameenah Bilal Phillips and Jameelah Jones. Good practical advice from an islamic perspective. http://www.islamhouse.com/pr/223540
Short Biographies, and reviews of this book, here: https://www.iiph.com.sa/products.php?listing=2&reqvals=Abu_Ameenah_Bilal...
Woman Under the Shade of Islam. Dr Jamal A BAdawi. Published by the Al-Birr Foundation UK. Argues that women are better served in Islam, than they are in the secular West.
Women In Islam "DIscover Islam" series, Bahrain. (A series of booklets) www.discoverislam.net
Women In Islam Vs Women In JudeoChristianity: The Myth and the Reality. Sherif Abdel Azim Phd.
The History of Human Marriage Edward A Westrermarck. Published 1925: a good historical account, which acknowledges polygamy. http://www.questia.com/PM.qst?a=o&d=10659043 (You have to subscribe to access texts.)
Polygamy (Religion/ moral philosophy/ social commentary) Ameyatman Das. The author is an American, who converted to Hinduism as a young man, and became personally acquainted with Bhaktivedanta Swami Prabhubad. In this paper, Ameyatman Das puts polygamy in the context of Vedic moral philosophy as a whole. He also argues that western society would be greatly improved, if it were adopted. An interesting study, which puts forth views not shared by some other Hindu writers. http://www.16108.com/dharma/Polygamy_1.htm
Enemies: A Love Story. (novel) Isaac Bashevis Singer. Made into a movie. A salesman in postwar New York is married to the Polish Christian woman who saved him from the Nazi's during the war. He also has a mistress. A previous wife died during the war, he believes--but then she turns up alive, looking for him.
The Travels of Marco Polo. The intrepid Medieval traveller encountered many places and peoples on his journey east. Polygamy occasionally mentioned, though he does not approve of it. Still a good read, after all these centuries. http://www.gutenberg.org/catalog/world/readfile?fk_files=1477438 (Also see Google Books.)
Things Chinese (Reference) J. Dyer Ball. Encyclopedic study of 19th century China, as seen through the eyes of a man who was there at the time. Look up "secondary wives" and "concubines" inj the Index, for a 19th century westerner's view of Chinese polygamy. First published 1893 It is a huge block of a book, which makes a resounding "thud" when you drop it on a table. Text available online: http://www.archive.org/stream/thingschineseorn00balliala#page/n7/mode/2up
What We Want for our Sisters we Want for Ourselves Dr Patricia Dixon. Polygyny is proposed for the African-American community.