Have you heard of Scrivener? It's available for both OSX and PC, and I believe there's an iOS version, too. It's really wonderful. The organizational tools are just incredible, and are only as complicated and involved as you want them to be.
I have! I like Scrivener as well and it's very powerful but its "does everything" functionality has led to some bloat in the UI department. Ulysses seems more thoughtfully designed but doesn't have the same breadth of features.