If you want a quick tour through the major Christian denominations, mixing history and theology and some positivist advice, you couldn't do better than this short book.
It is written by a Methodist pastor near Kansas City, and he does an excellent job of boiling down the complexities of the Orthodox, Roman Catholic, Lutheran, Presbyterian, Anglican, Baptist, Pentecostal and Methodist branches of Christianity in terms of how they got started, what distnguishes them, and equally important, what binds them together.
As a Presbyterian, my only reservation is that he put a little too much emphasis on the old (some would say outmoded) Calvinist doctrine of TULIP. While you Reformed theology insiders smile to yourselves, I will avoid boring the others wtih this doctrine, except to say that the "T" stands for "total depravity," the state into which we are all born (hah! -- take that, you Rousseauians).
This can be read in a day or two at most. It's accompanied by videos for each chapter, for use in small group instruction.