Means, Motive, and Opportunity

If you were to give consideration to a book based on the hundred novels you believe a writer should read, two conditions must be met.  The first one seems obvious enough.  You shall have read each of the hundred novels you use as a basis for your examples and commentary.  And the work in most cases shall have been in print for at least fifty years, giving it the time to earn out in terms not so much of finances as from stature.

You're leaving some weasel room for a few writers still much alive and producing.  Writers such as Louise Erdrich, Richard Price, Dennis Lehane, Denis Johnson, Joyce Carol Oates, and even though he says he's finished, nevertheless, Philip Roth.

One hundred novels a wannabe writer should have read, reread, learned from in terms of overall awareness, but also for the specifics you got from each of them.  Might be worthwhile to start a notebook in which you listed them, if only to see how well they stand up to your scrutiny.

Not sure of how to organize yet; perhaps having the provisional one hundred, then engaging the cross-talk and vetting process will provide an answer.

The first choice to come to mind is a solid one, Wilkie Collins's 1868 mystery, The Moonstone.  Significant among your reasons for choosing it, the narrative format, which is multiple point of view, not only providing a rich array of characters and introducing one of the earliest of detective investigators, Sgt. Cuff, but as well introducing another mystery staple, the gifted amateur, Franklin Blake.

Class was a matter of particular concern during the nineteenth century in England.  Sgt. Cuff had to approach the ingenue  victim, Rachel Verinder, with deference and tact, he being from the working classes and she his social superior. Indeed, Sgt. Cuff seems to have got precious little information from Rachel.  Even those interviews give the reader more social information than clue-related, crime-solving fact.

In significant contrast, Sgt. Cuff gets vital information from the butler, Gabriel Betteridge, and Franklin Blake justifies his narrative presence by his observations of the Verinder family and its background, as well as a stunning, surprise dramatic revelation of the sort that could well have provided inspiration for the contemporary crime novelist, Gillian Flynn, in her 2012 Gone Girl.

Every bit as prolific as his friend and publisher, Charles Dickens, Collins often comes out ahead in the assessment of which writer, he, or Dickens, had the better sense of humor.  Collins's portrait of Miss Clack, a poor relative of Rachel and her mother, Lady Verinder, gives us a dual vision of the nineteenth century version of a poor relative and a religious extremist, who cannot restrain herself from slipping biblical tracts under the doors of the various guests at the Verinder estate.

This is certainly a novel you'd want a beginning or intermediate mystery writer to consult for structure, characters, pacing, and its obvious influence on the mystery genre as it came bouncing along the bumpy country roads of the nineteenth century and into the urban sprawls of the big city in the twentieth century.

In your research for presenting this novel first to an adult class then to a group of undergrads, you became aware that a university scholar became interested in The Moonstone to the point of stopping her excellent translation of Dante's The Divine Comedy, in order to create her own version of the gifted amateur, Franklin Blake.  Thus did Dorothy Sayers introduce another amateur sleuth, Lord Peter Whimsey.

The Moonstone brings background and information about opium use and addiction, about India, about hypnotism, and about police procedure before the wave of interest in detective fiction began.  It in fact was one of the reasons why there was a wave of interest, one that intrigued Charles Dickens enough to try his own hand at the medium.