Like most people, I'll load the autosave for technical errors (misclicks and the like), or if I enter into a course of action that turns out to be a really monumentally bad idea ("No, Caesar, I won't give you wines -- oh crap, you just landed 40 Legionnaires on my shores and took 6 cities in 3 turns!"). Other than that, I will confess to reloading once or twice when one of my armies is in a city that gets culture flipped.
Oh yeah -- I also reloaded yesterday when I forgot I was in a wonde rrace and decided to switch from Monarchy to Democracy. As soon as I started the revolution, I remembered I was going to beat the Inca to Newton's by about 1 or 2 turns, and decided to hit the "undo button."