The Story of Christianity by Justo Gonzalez was very good and very easy to read. Technically it's two volumes but here you can get them in a single book:
Amazon.com: The Story of Christianity (9781565635227): Justo L. Gonzalez: Books
The history is written in a very conversational form, and not necessarily always linear--but that also makes it very easy to read and to get an appreciation for "while this was happening here in the west, over in the east..."
I found it to give excellent contours of history and it did a fair treatment of the Reformation and post-Reformation. It also includes some material on the expansion of Christianity into the world, particularly the Spanish expansions into South and Central America, which is something very often overlooked in religious history, which tends to focus almost exclusively on Western Europe and North America.
A high school or college student could handle it easily and probably find it interesting.
You could also glue all of Pelikan's histories together and put them on wheels for easy carrying in a single volume