I have found Fantasia to be useful, for the reasons identified earlier. The most difficult part of the engine to grasp fully is the complex economics; and I found that when playing the GC that I spent more time on military and diplomatic relations, and had difficulty understanding how to sustain a good economy and strong trade competitiveness. With Fantasia, you can deal with all of your internal mechanics for centuries, while also getting a feel for the dynamics of different nations and geographical settings: Eire for an excellent introduction to naval development; Inca for resource / inflation management; Iroquois in North America for land-based expansion.
I once played Iroquois as the dominant power in North America, owning / controlling and slowly populating the entire continent. Only when I chose to move south into Mexico did I encounter Incas (and their other allies), and began to get a sense of how to compete in a trade war. Eventually, I got sick of the Incas and declared war on them . . . or better prompted them to declare war with a trade embargo . . . in any case, Fantasia is a good, if somewhat formless, way to get a hold of your own development before interacting with other nations.