Dune (and series), by Frank Herbert.
The book, and the series, are simply awesome. The ideas, and so on, are really creative, and ot was my first book i ever read with over 600 pages.
King's Blood Four (and series), by Sheri S. Tepper. ??? ??? ???
I doubt anyone will have ever read those books, but it's (in my opinion) better than Dune, and the series overall has a nice history.
Ender's Game (and series) by Orson Scott Card. 8) 8) 8)
Yet another great series, but the quality deteriorates the further the story goes - which isn't much of a problem, the first one is so good it's still nice to read at the last one of the series.
(could be classified as PG15+, or something, i think. Anyways, not exactly something to give to your 9-year-old to read.) Time Enough For Love, by Robert A. Heinlein.
Sounds different for the rest you've seen me talk about, right? Well, it is. It's an envolving story, with some nice philosophy behind it.