[SWTXBelle]

We should probably specify that for the most part this discussion has centered on slavery in the Americas. Slavery, alas, has been around far longer (and continues today, for that matter).
I have always been intrigued by the enslavement of those who look like the enslavers. Surely it is easier to justify slavery if the slaves are "different". If you can think of the slaves as sub-human, or only in economic terms, it would be easier (I think) to live with your actions. But when the enslaved look like you - talk like you - and you don't have the "different" defense, your justifications would have to be more intellectual in nature a la the defense of slavery in ancient Greece and Rome.
I did Living History work, and one character I portrayed was an occupant of New Orleans under Union occupation. Doing the research was interesting - I haven't done any statistical comparisons, but I think I can make an educated statement and say that the attitude of southern women towards slavery and slaves was different than the male. It is remarkable how many primary sources show women who felt a certain similarity existed betweeen their role and that of their slaves - totally at the whim of men in terms of their lives, financially dependent, etc. (And NO - I'm not saying slavery = role of women. There is no doubt that is was much better to be a white woman than a slave. I am saying that women had a different take on it, and some of them were far more sympathetic than most men to the plight of their slaves).
Of course, if the slaves lived in marble palaces, wore silk clothes and ate bon bons all day it wouldn't matter - the problem with concentrating too much on how the slaves were treated is that it seems to imply that if they weren't being abused, then it was okay, or that it is wrong because people were abused when it was wrong because IT DENIED THE BASIC HUMANITY of the slaves in denying them the freedom that is a basic right for all men. And women, too!