For the theme of the conflict between inner desire and social constraint as expressed in late Victorian gothic literature, Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde and Wilde's The Picture of Dorian Gray are the stand-out candidates. Both novels use the supernatural to explore the desire to break away from social constraints and to explore what we would today call the "id." Both, however, stick firmly within the Victorian purview by affirming Victorian morality and restraint.
You might also explore the fear of "invasion of the contaminant." Late nineteenth-century writing reflects increasing concern about contaminating "others" invading Britain (and Western Europe) from other parts of the world, and Dracula is the prime expression of that anxiety transmuted into the supernatural in gothic fiction: Dracula and his invading army of the undead encompass all of the "aliens" the British feared were about to pour into the country and suck the "real" British dry. Bruno La Tour's The Pasteurization of France is an important text for understanding this fear.
Another theme might be the treatment of women in the late gothic: Wilkie Collins jumps to mind with his The Woman in White and The Moonstone. While not a gothic novel, Doyle's mystery The Sign of the Four has gothic elements in the exoticized Indian figures in the novel, from which Mary Morstan, the pure English woman, must be protected. You could also use or repurpose both Dracula and The Picture of Dorian Gray for this section. One way to order them would be to start with the earlier texts, such the Collins, and then work up through time.
I hope this offers some help. It seems to me that texts that are central to this exploration are Dracula, The Strange Case of Dr. Jekyll and Mr. Hyde, and The Picture of Dorian Gray.