Advanced Genre-Sort Question

This is my second year in a genre sorted Middle / High school library. The first year went great and brought very positive results and compliments. It works, but I am still tweaking and changing. My driving goal is to improve collection accessibility for all users - to help great books jump into readers hands!

My question is about how to catalog Classic Fiction,  but think it is important to understand my set-up first in order to answer.

My current Genres are:

• Sci-Fi
• Fantasy - (FAN - includes fairy tales, high fantasy, and anythng else that does not fit other sub-genre's)
• Contemporary Fantasy (CONFAN - AKA Urban Fantasy - Current time period fantasy - often include elements of paranormal but tend to add magical element not found in paranormal - often include or rely upon some sort of mystery 
• Paranormal - (PARA - verging on reality but that cannot be explained - ghosts, body/identity swapping, angels, vampires - often synonymous w/ romance)
• Horror - (HOR - 
• History - (HIS - If primary genre is history - If primary genre is Mystery or Fantasy in another time period, see below regarding secondary genres)
  
• Mystery - (MYS - 
• Action/Adventure - (ACT/ADV - A catch-all category that includes survival, travel, hunting, war stories (cataloged here with HIS secondary label), and even some soft science fiction and superhero stories -- This section is right next to my Sports section and I use it as a go to for boys and reluctant readers) 
• Sports - (SPORTS - 
• Real - Realistic, modern fiction. Anything set more than 15 years earlier would have a secondary Historic tag 
• Humor - Tends toward middle school with Wimpy Kid, etc.
• Graphic - I segregate my graphic with the following call number prefixes and find that it works great!
• GN - includes original graphic novels and Manga (my current manga collection is very small!)
• GNA - adaptations of previously printed materials
• GNN - Graphic Novel Nonfiction (by Dewey)
• COM - Comic - (DC, Marvel, comic books)
• CAR - Cartoon - (Garfield, Peanuts, etc)

Each of the above groupings on are shelved by author in their own area of the library. My twist, upgrade to the classic genre sort, is in identification of secondary genres. Whenever appropriate, secondary and tertiary genres are also marked on the spines. This allows readers to have a quick idea what might be inside. They know up front, whether they are looking at a Fantasy / Action Adventure or a Fantasy / Romance, etc. In addition to the genres listed above, I have identified three sub-genre, listed below, that I add as secondary and tertiary tags but do not shelve separately. I am sure the photographs attached will help explain this better.

• Romance
• Thriller
• Classic
• I may add Dystopia, Apocolyptic, & SteamPunk at some point
• I haven't found a need to add Fairy Tale, High Fantasy, or others, but am open to these and others in the future

We are getting closer to my questions. Please remember my driving goal is to make all titles discoverable through serendipity by readers who show interest in certain types of books. Looking at Classics, it seemed obvious to shelve:

• War of the Worlds, A Wrinkle in Time, Handmaid's tale, and other in the Sci-Fi area with a secondary Classic tag
• Lord of the rings, The Hobbit, The Wizard of Oz, and The Neverending Story in Fantasy area with a secondary Classic tag
• Call of the Wild, Lord of the Flies, Adventures of Tom Sawyer, The Outsiders, and others in Action Adventure with a secondary Classic tag

It also seemed obvious to shelve To Kill a Mockingbird, Grapes of Wrath, Little Women, and others in Historic with secondary Classic Tag as I felt students who were not necessarily interested in the classics might still enjoy these stories. 

My problem begins here. I seem to trend toward pushing more and more classics into subcategories and then revolting against myself. The revolt is based upon my theory that cluttered shelves and the illusion of choice reduces student's ability to make good selections or have positive serendipitous experiences. My goal is to limit options to titles that truly belong together.

Don Quixote, Elmer gantry, Gulliver's Travels do not get read except by the .001% of students interested in reading Classics so these, and books like them should be foundations of a Classics Collection. I can add to these, Crime & Punishment, Hunchback of Notre Dame, Ulysses, and more. I would like to pull Shakespeare and Homer out of the 800's to add to the Classic Collection. I believe this will give it some weight and draw increased attention to its existence.

There is a list of much more popular books like The Pearl and Catcher in the Rye that we read as classics, not as historical fiction or any other common genre. It makes sense to me to locate these in the Classics Collection

Which brings me back around to titles that are not as easily categorized and the reason for my call for help. Considering a middle & high school audience, I am struggling with the titles below and many more. I am not sure where they fit best and need suggestions.

• Scarlet Letter and Pride & Prejudice and many others are historic but usually read as a classics

• Grapes of Wrath, Little Women, A Tree Grows in Brooklyn -- historic or classic?

• Uncle Tom's Cabin, & The Good Earth,  - historic or classic?

• Frankenstein, Dr. Jekyll & Mr Hyde, Dracula, & Wieland in horror or classic as primary shelving location?

• The Lost World by Arthur Conan Doyle is fantasy or maybe sci-fi, but should it be considered classic?

• Where should Huckleberry Finn go?  (Think middle & high combined audience. Do I put it in Action Adventure with Tom Sawyer?)

• The Three Musketeers & Man in the Iron Mask

• Great Gatsby?

• My list goes on . . 

Any suggestions or ideas would be appreciated. I am struggling to draw lines and in search of guidance and wisdom from others. 

Thank you for taking the time to consider this situation and offer me some guidance.