Has your book group tried any short story collections? You could choose an author to concentrate on or assign a story to each member, or simply assign a collection and let your members report back to the group.

Among the missing by Dan Chaon

Don't tell anyone by Frederick Busch

The PEN/O. Henry Prize stories. 2011 by chosen and with an introduction by Laura Furman; with essays on the stories they admire most by jurors A. M. Homes, Manuel Munoz, Christine Schutt

A day in the life of a smiling woman: complete short stories by Margaret Drabble; edited by José Francisco Fernández

The science fiction hall of fame. Volume 2B: the greatest science fiction novellas of all time by chosen by the members of the Science Fiction Writers of America; edited by Ben Bova