There is always the question about the sequence. My own idea is: the Yi is an ancient moon-almanac, starting at new moon, and giving the meaning for every day of two consecutive moon-months. The first one yang, the second one yin, like the Chinese signs. In the course of a sun-year, there are 6 of those double months, each with its own 'color'.
It might not deliberately have been made like that. But many important sequences have the same base, a universal pattern.
Danny van den Berghe made a very good website with an explanation of King Wen's sequence of the hexagrams: www.ping.be/icrea/ I like this one very much, it is convincing and beautiful.
A difficult page (you are warned!) has been made by Chris Lofting. I heard several arguments which made sense, but I am afraid I am not intelligent enough to oversee it. But maybe you are? He divides the 64 hexagrams in 8 octets.
THE INVISIBLE LANDSCAPE, MIND, Hallucinogens and the I CHING, by Terrence & Dennis McKenna. Very convincing.