Not to mention it goes more in depth with how Luke became a jedi and you see he was fully trained by ROTJ, the movies can only shove so much into it where with novels you can add so much more because the only thing a writer is limited by imagination.
Totally agree. If someone reads books just for the basics of the plot, I'm not sure why they'd read books at all. Websites can do that about 100 times faster. The novelizations, on the other hand, significantly expand the universe (pun intended) and are well worth reading, in my opinion.
As for the Zahn books... this won't be a popular opinion, but I'll say it anyway...
I liked the Zahn books. They were fun and when they first came out they were pretty much the only EU we had. That said, I honestly don't see them as great works of Star Wars lore. Those books, in my very humble opinion, feel like science fiction books that take place in the Star Wars reality, which isn't science fiction. If you're a fan of pure science fiction, I think you'll like the Zahn books. But if you're a fan of the cowboy side of Star Wars... or the high adventure side of Star Wars... or the mystical side of Star Wars... the Zahn books don't really bring that emotion, for me at least.