Dune

I tend to avoid long novels. It seems excessive length is most often a sign of poor editing rather than excess content. The Harry Potter series is a great case in point. The middle books were both the longest and the most tedious.
Thus, it was with some apprehension that I chose to tackle Dune.
When thinking of Dune, the first thing that comes to mind is Sting running around the sand with a bunch of worms. (This in spite of having never seen the movie.)
The book itself did not immediately give me warm fuzzies. It created a grand world, with different classes of people and beings.
Another Lord of the Rings? Ughh. I'm sure with enough time that somebody could appreciate the whole Middle Earth thing. But, there has to be some desire to actually spend that time. And I'm a little reluctant to slog through that a pile of books before deciding. "Uh. Yep. I really don't like it."
Luckily, Dune turned out to be pretty good. I still got lost in some of the details of the planetary conditions and family relationships. Luckily, it did not seem to matter.
The novel is set on a desert planet that happens to have a rich supply of an addictive "spice". Water is in such short supply that it has assumed a high value and is eagerly conserved. Out in the desert live giant sandworms as well as "native" people who have a culture adapted to the conditions (as well as an "addiction" to spice.)
In to this setting, we place our hero, Paul. He is of noble birth and trained in special mental skills, fighting and (by his mother) "witchery". His grandfather attempts to have him and his mother killed. They escape, fall in with the "natives" and eventually lead the natives to capture the "city" and become ruler of the land.
Among his gifts, Paul also has the ability to see in to the future. His visions of the future, however, appear in varying degrees of clarity, and are subject to change based on events. (Thus, they become more akin to "prophesy".) He even manages to "see the present" at the end of the novel and act as would benefit his people in the situation.
The novel does a pretty good job of wrapping "most" things up at the end, providing some finality, while still providing many possible avenues of exploration in sequels. It was popular enough, and thus there are plenty of sequels.