My mother has belonged to the Mystery Guild subscription book service for years, as well as a local book discussion group in her small East Tennessee town. I haven't been able to find a comprehensive listing of all such book clubs around the country (and world), but I imagine the numbers are quite impressive. Publishers are beginning to take notice of these book clubs, as a recent New York Times article indicates. Khaled Hosseini goes so far to say that the success of The Kite Runner is due to such groups, as the novel wasn’t being read until they got hold of it.
Mystery book discussion clubs are an important subset, often meeting at public libraries or independent mystery book stores. Mary Alice Gorman, co-owner of Mystery Lovers Bookshop, Oakmont, Pennylvania, offered advice on titles for mystery book groups to Shelf Awareness:
"At Mystery Lovers Bookshop we have several book groups who meet here over food...an important factor. The oldest one is the Women Lawyers Group who celebrates 14 years in May. The others who have all met for more than 10 years--Second Thursday, Second Monday, History, No Lunch Bunch--and they read mysteries, too, while the Eclectic Book Group reads just that. There are other groups for whom we make suggestions when asked and order all books. Each year about a half dozen other groups come to the store for a mystery field trip. So you can see we have much experience with what works and what doesn't. We try to suggest books that prompt good discussions, provide some new and interesting information and hold their own among the readers of the more 'literary' novels."
As an example of what works well with the group, Gorman mentions Nancy Pickard's The Virgin of the Small Plains, which sustains "crackling suspense," depicts the setting with the sure grace of a gifted writer, and provides a plot and characters which promote a discussion of the fate born of secrets.
To illustrate what doesn't work as well in book groups, she references humorous mystery books like those by Janet Evanovich. While mystery readers do love them, the discussions tend to be limited to punch lines and favorite scenes. Groups who read Sayers or Christie also report the same sort of flagging discussion.
For four additional examples of novels that she feels lend themselves to discussion, including books by Ken Follett, Lisa Scottoline, Laura Lippman, and Dennis Lehane, you can visit the Shelf Awareness web site.
I just updated the Book Clubs section of The List on the blog, by the way, so be sure and check out the links there. The section on individual book clubs isn't comprehensive, by any means, but it's a start. There are also some links to information on how to start and maintain your own book club.