Approaching the end of Pope Francis's Open Mind, Faithful Heart bookclub here some suggestions for a new choice.
The Last Letters, Thomas More - Written during the fourteen months he was waiting the execution at the Tower of London those letters are his spiritual testament and the memories of a man who acted accordingly to his conscience. The Kindle edition has 24 letters that can make a 24-week bookclub. The discussion can be expanded to the trial of Sir Thomas More who used his lawyer skills in his defense (I never understood why he was denied a proper trial by jury according to the Article 39 of the Magna Carta).
Damien the Leper, John Farrow - "John Villiers Farrow, was a film director, producer, novelist and screenwriter" and father of Mia Farrow. St. Damien of Moloka'i died in Hawaii (at the time Kingdom of Hawaii and not part of US), he was a missionary who volunteered to assist the population of Moloka'i, a colony used as forced exile for Hawaiian people suffering from Hansen's Disease. The book also tells part of the history of St. Marianne Cope from Syracuse, NY. This book will definitely cause an impact in your life. (Bonus: the historical and epidemiological aspects of leprosy) - Has 17 chapters, a prologue and epilogue. ~20-week bookclub.
The Song at the Scaffold, Gertrud von le Fort - Tell the history of the martyrdom of 16 carmelites at Compiègne in the guillotine during the intense years of the French Revolution. This book written in 1931 inspired the play by George Bernanos. This work shows the virtues and weakness of the sisters and their spiritual growth in face of the death they did not seek. - The number of chapters varies according to the edition. I guess it can be good for a 14 to 16 week bookclub.
The Secret of the Cure D'Ars, Henri Gheon - Although the ultimate biography about St. Jean-Baptiste-Mary Vianney AKA "Curé d'Ars" was written by Francis Trochu, the book by Gheon has the advantage of being a shorter biography focused in the saint as a priest (above all he's the patron saint of all priests), setting aside some detailed biographic aspects. The two main disadvantages of this book for a bookclub is being relatively difficult to find and the large chapters. Depending on how the chapters are separated could be good for a 20-week bookclub.
Saint Teresa of Avila, Marcelle Auclaire - One of the most complete biographies of the the founder of Discalced Carmelites and mentor of St. John of the Cross. In Spain, during those years, many saints appeared and the book tells some of their histories including one quote I used in a September comment "I brought the body of our Lady the Queen carefully guarded from Toledo to Granada, but to swear that it is herself, the woman whose beauty admired me so much, I dare not. […] Yes, I swear (that’s her), but I swear too never more serve a master that might die." (Duke of Gandía later St. Francis of Borgia).
Bonus
A Doctor at Calvary, Dr. Pierre Babet - AKA "The Passion of Our Lord Jesus Christ As Described by a Surgeon", Dr. Babet was a french surgeon that using forensic pathology techniques performs a detailed virtual authopsy based on the Shroud of Turin (see also Wikipedia article). It would make an interesting bookclub subject for 14 to 21 weeks.
Vessel of Clay, Fr. Leo John Trese - An hourly account of the daily life of a priest working in a rural US area. His struggles, the prayers, the meditations, the casual events of life. A very nice read and good material for a book club since it's very well segmented.
Larger books
The 12 volume History of the Church by Henri Daniel-Rops - Too long ~6000 pages.