I was turned on to Dune by a high school teacher, but even though I went as far as God Emperor, I could never really get into it, and ultimately sold all of them off to a used book dealer. Something about the inside-out morality: mind- (and body-)altering drugs, assassination, and war are OK, but "Thou Shalt Not Build Artificial Intelligences"? Abbesses who wield an agonizer and an instantly-fatal poisoned needle that "kills only animals"?
I'm with "Nerys Myk" on Alan Dean Foster and the Humanx Commonwealth series. Foster is probably my favorite living author, and I find him grossly underrated. His opening line, "The Flinx was an ethical thief, in that he stole only from the crooked" (The Tar-Aiym Krang) is right up there with "In a hole in the ground lived a Hobbit." And "It's hard to be a larva" (Nor Crystal Tears), and the entire first paragraph of Sentenced to Prism, aren't too shabby, either.