I got two non-fiction books while I was on my trip. The first is The Heart of Islam by Seyyed Hossein Nasr. This book provides an excellent overview of Islam and the meaning of its teachings in regard to such issues as relations with non-Muslims, family and society, the Shari'a, and jihad. He also discusses the diversity of the Muslim world. Nasr wrote it in the wake of 9/11 for the express purpose of spreading knowledge about Islam.
The second book is Indians in American History. I found this to be an excellent book as well. It provides an overview of the history of Native Americans and their interactions with European colonists and with the United States. For law nerds like me, there are also sections about the status of Indian tribes in U.S. law. Some of it is very depressing because the U.S. has a pretty shameful history in regard to the treatment of Native Americans. I bought this book because I became interested in the history of Native Americans in the regions where we visited on our trip and I wanted a good overview.