The Story of Christianity (vol. 1 and vol. 2 ) is long, but very readable, especially if you don't need to learn lots of exact names and dates like you'd have to for a class. I haven't read Church History in Plain Language , but I've heard good things about it, and it's about half the length.
Obligatory self-promotion: My book, A Flexible Faith , includes a brief profile for a relevant historical figure in every chapter. So, for example, in the chapter on origins of the earth we meet Augustine; it's John Wycliffe in the chapter on the Bible; Dorothy Sayers in the chapter on foreknowledge and providence; John Chrysostom in the chapter on wealthy and poverty; and so on. It's by no means a comprehensive history, but it'd give you a taste of things.
I like Justo Gonzalez' The Story of Christianity parts I and II
Here are a few:
The Story of Christianity by Justo González
Buddhism Plain and Simple by Steve Hagel
Islam in Historical Perspective by Alexander Knysh
Following Muhammad: Rethinking Islam in the Contemporary World by Carl W. Ernst
Science and Religion: A Historical Introduction by Gary Ferngren