Inferno by Dan Brown

It may not be great literature but it is a real page turner.  This romp with Robert Langdon through Florence, Venice and Istanbul doesn't just spin around the abuses of power.  It tackles a real and fascinating issue - the possible consequences of our exploding population - not to mention the possible abuses of genetic modification and the whole notion of the moral conflicts often inherent in scientific discovery.  Apparently Brown has decided that since he probably is going to be holding your attention for a good chunk of time, he ought to be reasonably thought provoking - with the usual twists and turns to keep you confused about who is the good or bad guy.  If I were going to be visiting any of these cities, I would for sure be looking for all the secret passages and hidden messages.  I doubt that his books often end up on "book group favorites" lists but this one is full of possible discussion starters.