My $0.02 worth:
-- A general thumbs-up on most of Xia's suggestions.
-- Caravans should either be abstracted away (as per suggestions above: autorestart after a period) _or_ they should become full-fledged (though auto-moving) designed units that resolve tactical combat just like any other unit and can be built increasingly more powerful as techs advance. If EWOM is going to have 'real' ships someday, it might as well have 'real' caravans.
-- Succession: here's another vote in favor of it, because I think it could make EWOM a truly different game. The possible complications are delicious, particularly when you throw in arranged marriages: wars of succession, civil wars, chunks of your empire suddenly going over to another empire because your only daughter is married to that empire's sovereign's eldest son. George R. R. Martin has done a wonderful job of outlining all the succession nastiness that can occur in the Game of Thrones series -- and those novels are _all_ about the characters rather than the kingdoms and empires per se. It means you need to carefully think about who marries whom; it also means that you'd better be carefully grooming your own heir so that things don't fall apart when you pass on. And (as per comments), it means there's a real risk of assassination of your heir(s), either from younger children or from outside factions.
-- Minor factions: also thumbs up. City-states with unique techs, resources, spells, objects, whatever. You can gain access to those only by trade, by treaty, and/or by intermarriage (and the access method may change depending upon what it is). However, if you simply trying to march in and conquer the faction, some or all of those unique things vanish forever. This means that you have to compete diplomatically to gain access, and should you do so, you have to protect the faction with your military to keep other major factions from marching in and crushing them to deny you that access. Oh, and with the right intermarriage (your son to the minor faction's sov's daughter), the city state and all its unique things become yours when that sov dies. if the marriage is the other way around (your daughter to his son), then when the sov dies, you have easier/cheaper access to the unique things, etc.
-- For that matter, permanent alliance with a major faction by intermarriage should be a possibility: you marry your son to that faction's daughter, the sov there dies, and presto! that kingdom/empire becomes a very strong ally. Of course, your son may get ambitious and be plotting to take over your kingdom from your heir when you die.
-- And this gets back to something Xia touched upon: we need some relatively simple way of modeling relationships among the sovereigns, their various descendants, and the champions, and how you can try to improve or solidify those relationships. Can you imagine being in a tactical battle -- and suddenly having one or more of your champions or even your children/grandchildren switch sides? That would certainly make the children and champions far more interesting, whereas now they are mostly just interchangeable units, albeit more powerful and flexible, that you hire once (and you don't even do that for your kids) and move in large stacks.
-- For that matter, you may face assassination attempts as well: from the other side, from your own descendants, and/or from disgruntled champions. Again, modeled as tactical combat; it forces you to keep very loyal troops/kids/champions around you, especially early on before you have come into your full powers.
That's it for now. ..bruce..