Anyone interested in speculative world-building could do worse than reading Carroll Quigley’s The Evolution of Civilizations.
I just finished chapter 5, which is for such purposes a scaffold on which one can construct a fictional society – whether on the small scale (an organization, corporation, colony, etc.) or large (an extrapolation of current civilization into a future history, a galactic empire, an entire alien civilization, etc.).
As it happens, Quigley articulates in the earlier chapters (whether its his invention or he simply applies it, I don’t know) the PERSIA template that we applied to the development of the Ares Project future history. PERSIA is a mnemonic for six broad subject areas one should consider in examining a social entity or period: political, economic, religious, social, intellectual, and aesthetic. (Note that this is how I learned it in high school – Quigley adds military and subsumes aesthetic under intellectual, which makes more sense but wrecks the mnemonic.)
The earlier chapters are interesting, but consist of laying the groundwork for what starts in chapter 4 and really blossoms in chapter 5. The former chapter lays out his concept of instruments vs. institutions, and specifically the instrument of expansion central to all civilizations. The latter chapter is an exploration of seven stages through which each historical civilization has progressed, and how different civilizations have fared against each other (or against uncivilized societies/cultures) at differing stages.
So far, a much, much better read than Tainter’s oft-recommended (but probably seldom-finished) Collapse of Complex Societies. And it’s a quarter of the price.