The original Frank Herbert Dune works are probably the deepest researched and most thought out series of books in science fiction. Everything you need to know about the deeper layers of politics, religion, control, ecosphere, not to mention an amazingly rich and deep world more realistic than any other in literature, is contained in those six books. It's pretty damn entertaining too. I first read Dune while on a cross country cycling journey. I got the first Dune in west Texas, from a toothless, extremely aged straw cowboy hat wearing dude, whose face was shrivelled in on itself like an old pumpkin. He was sitting in a very low wood rocking chair, and when I offered to trade a book for the Dune book he had (the only sci-fi book amongst an entire shelf of Louis L'amour books) he said "I'll only do it for two, gotta trade two for one." So I did it, and found myself stopping in blasting desert heat of West Texas to steal a few more pages - just get to the end of this chapter, then I'll put it away. Then at night, tired and beat from the long straight road, I would hide in the sleeping bag like a little kid, with flashlight, poring over that amazing book. I finished it fast, and ended up trading it for the next Dune book, at another town in Texas. My whole ride across Texas brought me almost in completion of the series. I read the God Emperor of Dune in Austin, staying with a friend, and still remember how much I enjoyed that one, so different in the series, but so compelling. By the time I crossed the border in Louisiana, I had the last two of the series in my possession...
So what I'm saying is that I would definitely recommend Dune. But with a warning that the first book might be a bit tedious to get through, where the second one is more old school sci-fi with lots of action.