My favorite stories are usually ones that have a bigger world behind them, a story behind the story that becomes even more engrossing the more you study it. Things like J.R.R. Tolkien's Silmarillion (I've read it twice!), the T.V. show LOST and some Anime series like Evangelion. I think this is apparent in my writing style. The main world I write in: Echowake, spans thousands of years with vastly different characters and settings throughout. The whole thing started out with a basic concept:
"A broken world, covered in scorched earth. Massive Air Whales calmly floating across the sky, while a great evil is stirred."
A simple enough concept, but was enough to get a great spark going. I've been diving into and building in this world for years and have come to love it. I hope you will too.