In recent posts by Cynwise and Shintar (and the comments associated with them), there's been an interesting debate about whether the Forsaken could be considered evil. I'm not inclined to buy the "an entire race is evil" theory, but it does raise the question of whether the leadership of the Forsaken (which is pretty much Sylvanas alone these days) are evil. At the core of this is the use of blight and the extent to which Sylvanas intends it to be employed.
1. Did she know of & approve of the development of the blight in general?
I don't think many people would dispute that.
2. Did she intend to use it against the Scourge?
Again, I'd say yes.
3. Did she intend it to be used at Wrathgate?
It's hard to be sure about this one. My suspicion is that Putress was given instructions to use it if he thought there was a good chance of taking out Arthas in one hit. Would anyone have complained about the loss of Bolvar and Saurfang Jr if Arthas had been defeated at Wrathgate?
OK- perhaps Varian would have made a fuss for form's sake, but one suspects that in private he'd have been quite happy to sacrifice a potential rival in return for a quick win against the Scourge. Was Bolvar a potential rival? If he got home and saw what Varian was up to in Westfall, quite possibly.
4. Did Sylvanas intend it to be used as a weapon against the living at some point should it prove necessary?
Again, I'd say yes.
5. Is the eventual use of blight against the living her plan A, or merely a "don't mess with us" deterrent that would only be used as a last resort?
Pre-cataclysm, it would be possible to argue this one either way. However, the invasion of Gilneas clearly shows that Sylvanas intends to deploy blight liberally as a weapon of war. Whether this is fundamentally more evil than disembowelling people with spears or charring them to a cinder with fireballs is a question for another day.
6. Is Sylvanas "scheming quietly about how to destroy all life on Azeroth and how to become the Ultimate Queen of Uber Evil".
The key part of this question may be the word "is", i.e. the use of the present tense. As Rades has pointed out in his series of posts on Sylvanas, it's entirely possible that she has changed as a result of her raising by the Valk'kyr; indeed the "Sylvanas" we see now may not even be the same person as the one we saw before. The Arthas part of the Lich King has been defeated, but it's less clear that the Ner'zhul part has been.
Perhaps the clue lies in the suspicious changes of appearance she's undergone over the years. Are these really the same person?
Who'd have thought that joining the ranks of the undead made your lips progressively poutier?