I only restarted the first few times I played, and wanted a nice easy game just to see all the way through. I did this on my first game ever (with the Greeks) to get some Gold in the surrounding hills, so those commercial bonuses would add up early on, but it turned out that the rest of the surrounding territory was pants, anyway. Had to risk an early war with Rome as a result, to get some nice fertile land, but it paid off.
The rest of the time I've stuck it out, though sometimes I've given up later on if the going's got impossibly tough (or my n00b skills fail me, one or the other) around late Medieval times or something.