Frank Herbert paid his readers the compliment of assuming they were intelligent people who could think things out and reach conclusions for themselves, without having it all spoonfed. And that's even with the very detailed Appendices at the back of the novel.
What's ironic about this is the number of people who have grouched at me since Villeneuve's first movie when I mentioned not liking the pointless genderswap of Liet-Kynes and that Chani's father is supposed to be a man, not a woman, and women don't have that kind of power in either the Imperial court or among the Fremen, anyway. They swore up, down, and sideways that there's no proof of any relationship between Chani and Liet-Kynes, when there absolutely is - Frank Herbert's own dialogue in the novel, which was repeated word for word in the Lynch movie, when Paul and Chani meet: "I am Chani, daughter of Liet."
The book I've found with that much re-read value is Cyteen, by C.J. Cherryh. It's part of the Alliance-Union series, and takes a deep dive into so many fields of hard science and the social and psychological sciences that indicate what an incredible amount of research Cherryh must have put into it.
The parts of it that reminds me most of Dune are the terraforming and the parental replicate/psychogenesis projects.
Terraforming: Humans settled Cyteen, even though they have to live under a dome of sorts - there's nasty stuff in the native atmosphere that gives humans cancer. They were planning to terraform it until they discovered something that could be used to extend the human lifespan to approximately 140 years, and most of that time would mean having the body and mental capacity of a 30 to 40-year-old healthy human. Only at the very end would people go into a few weeks of "rejuv failure" and age rapidly before dying.
So the question is: Is terraforming ethical? Is it ethical to manipulate a planet's ecology for the benefit of humanity when humans are perfectly able to live on generation ships and star stations? Who knows what Cyteen's native life might have evolved into if not for human interference?
The other thing is psychogenesis. The main character of this novel, Ariane Emory, is a 120-year-old certified genius who has done pioneering work in designing whole cultures of people, right down to genetics and what they probably like for breakfast. She's incredibly intelligent in so many fields, but she's picked up enemies along the way. When she's found dead, there's so much of her work that still hasn't been completed, and there's a project that's started to recover her.
Ariane is cloned as a baby, being gestated in an artificial womb and birthed in a lab. From that time on, her life is patterned as closely as possible on her predecessor's life - and there's a huge database of information on that. The original Ariane Emory wanted to be brought back like this, and planned for decades to make sure it happened. So "Ari 2" grows up as a child, not knowing all this until she's old enough to understand, while her guardians teach and train her to learn what her predecessor knew, and they use biochemistry and "endocrine theory" to tweak her personality to match her predecessor (ie. if Original Ari got sick at age 10 and that deprived her of a treat and she was upset about it, her guardians made sure the same thing happened to Ari 2).
The result is that Ari 2 is very close in personality to her predecessor, but a bit nicer and more considerate, due to influences her guardians couldn't control as closely as they'd wanted to. Granted, it takes many years (Ari 2 is 18 at the end of the novel) as opposed to a few months and one traumatic flash of memory for a Frank Herbert ghola, but it's more realistic in my view. The idea that Duncan the Umpteenth, several thousands of years after his original existence, could suddenly remember everything that happened to him just because of a few cells being regrown in a Tleilaxu tank and undergoing a traumatic bit of psychological manipulation based on that... well, after reading Cyteen, I realized that Cherryh did it better than Herbert.
That said, Duncan Idaho is still my favorite Dune character.
