OK, here is a list of books that I would think are good options. I think books on strategy would be most appropriate for a book club.
HOW TO REASSES YOUR CHESS, Jeremy Silman: A lot of folks have already read this. Many swear its the best book ever written, but many say its full of mistakes. I'm a bit reluctant to read it because Silman is currently working on the next edition, in which he is replacing 90% of the examples. Still a good option though.
AMATURE'S MIND, Jeremy Silman: Also a popular book and highly rated book.
LOGICAL CHESS, MOVE BY MOVE, Irving Chernev: Greatly loved book. Maybe a little too beginner-level for most of us.
MY SYSTEM, Aron Nimzowitsch: The classic.
ART OF ATTACK IN CHESS: The manual on how to attack. This would be my vote. (Opps. We're not voting yet...)
UNDERSTANDING CHESS MOVE BY MOVE, John Nunn: Very advanced, but highly rated.
THE MIDDLE GAME, Max Euwe, H. Kramer, and Lou Hays: 2 books.
50 ESSENTIAL CHESS LESSONS, Steve Giddins: Good book and would be easy to divide up into a lesson a week.
THE POWER CHESS PROGRAM, Nigel Davies: This training program is already divided into a weeks and months.
THE ART OF THE MIDDLE GAME, Paul Keres and Alexander Kotov: Excellent book, and short enough to be a good trial starter.
HOW TO BECOME A DEADLY CHESS TACTICIAN, by David Lemoir and Ken Lemoir: Not very popular, but very enjoyable. Its more on attacking and sacrifice than tactics.
Please submit any book you feel would be a good option.