I recently started reading the Star Wars Novels - the so-called Expanded Universe of Star Wars... I was pleasantly surprised by how much I enjoyed the novels & I find that I love them much more than any of the films. I now think of the books as STAR WARS, while the movies are random, poorly executed TV movies of the week adapting random novels. I have tons more to read & I look forward to it, but here's how the Star Wars Universe seems to be set up {from my point of view, at least}, and as you can see, I'm really just reading the prequel era novels; I own almost all the others, but I'm trying to read them all in order.
WAY BEFORE EPISODE I: THE OLD REPUBLIC
LESS THAN 100 YEARS BEFORE EPISODE I
BEFORE THE CLONE WARS: EPISODE I & BEYOND
EPISODES II - III: THE COMPLETE CLONE WARS SAGA
BETWEEN EPISODES III & IV: "THE DARK TIMES"
EPISODES IV-VI
BEYOND EPISODE VI