I was playing a lot of Rome: Total War, a game that is, if anything, more time consuming than Civ. Basically, you start as a Roman faction in the middle Republic (when they had conquered all of southern Italy and eastern Sicily) and have to take over 50 provinces and Rome itself. It makes a valiant attempt to be historically accurate, certainly enough that it isn't annoying.
As a pure strategy game it takes ages to play since your units can take a long time to move from one front to another (which is reasonable). What makes it even more incredibly time consuming is that you can play each battle as a fixed-resource RTS (a lot like the old Myth games). This is worth doing for really close battles as most of the time the player does a better job than the CPU (as is so often the case). I can't imagine that anyone plays all of the battles, of course, since that would require ridiculous amounts of time on the hard levels but it's cool to give them a go.
After a lot of playing this one I fired up Barbarian Invasions, the expansion pack. It's a surprisingly different game. Essentially the main difference is that when you take the last city of a barbarian tribe (which are most of the groups you will come across) they become a horde which attempts to find a new homeland, sacking cities as they go. They will eventually capture and settle (rather than sack) the three cities required to settle into a new homeland but in the process they can disturb other groups. You can have a ripple effect as a horde creates hordes out of other tribes and they spread across the map. Starting as the Hun horde you can easily set off the Goths, Vandals, Sarmatians and Roxolani. In one game I did this and when I finally made contact with them again (after they had settled) they had conquered all of Europe from Dacia to Aquitania, leaving a devastated Western Roman Empire behind them. Actually, playing this game is rather depressing in some ways as the remnant empires keep splitting and buckling under the pressure of the hordes. The Huns are basically all conquering and by far the easiest tribe to play but it seems sad to watch the Western Empire riven by rebellion as you march on Rome. Still, who can say that the fall of the empire was necessarily a bad thing for us today (as opposed to people then). There is no way to know what society might have become and those who hold that we would be living in an Eastern autocracy have a rather simple view of what happens over nearly two thousand years.