Hm, going from what you listed already, here’s what I’d recommend…
Rafael Sabatini - Scaramouche and Captain Blood to start, they’re great swashbuckling adventures much like Dumas’.
Horace Walpole - The Castle of Otranto - the first gothic novel! Love, death, taboos, giant helmets falling on people!
Bram Stoker - Dracula
Mary Shelley - Frankenstein, or, The Modern Prometheus
James Branch Cabell - the Poictesme novels. Pre-Tolkien fantasy, and again, much swash is buckled.
William Hope Hodgson - The Night Land. Adventure, romance, and the foundation of the Weird Fiction and Dying Earth genres (Lovecraft, Vance, et al). Okay, I’m a little biased toward this one (Mirdath is a character), but not enough people have read it!
Honore de Balzac - short stories. They’re short, but there’s a lot of them. More decadent than the previous, but there’s nothing wrong with that.
Fritz Leiber - the Fafhrd and Gray Mouser books (stop before Knight and Knave, it was horrible). Trashy, pulpy sword-and-sorcery fiction has never managed to be as good or as fun as it was the first time.
Charles Palliser - The Quincunx. It’s zombie Dickens! Seriously, I can’t think of anyone who’s managed to be more like the other Charles than this author – he may be even more Dickensian than Dickens himself.