I would recommend anything written by Frank Herbert, who is best known for his 'Dune' books. In all of his works FH tries to make a point, using the story as a vehicle (unlike some authors who put the story first then decorate it with some 'big' idea). He runs a *little* deep, and so you will need to use your noggin a little. Also, his stories don't end up with everything back in place and happy (i.e. Asimov), as like in the real world things change and there are always consequences (mostly unforeseen and unintended).
Note that the books written by his son, Brian Herbert, are garbage and demonstrate that talent isn't always inherited.
Jules Verne and H.G. Wells are long time favorites.
Not really big on Robert Jordan's Wheel of Time and I cringe
anytime someone compares WoT to LOTR. Please!
Robert E. Howard's "The Coming of Conan the Cimmerian" was a good light read.
Neil Gaiman's Sandman grapic novels are different but thought provoking.
D'Aulaires "Book of Greek Myths" is great, and can't wait to start sharing it with my kids as I remember reading it as a child.