I dunno. Vader didn't seem too impressed with the Death Star as compared to the Force, but then he had a lot of respect for Tarkin, and the Death Star was really the pinnacle of The Tarkin Doctrine of "Rule by Fear". I feel like he would have used them had he had access to them.

Luke refused Vader's offer to join him because he was a stronger person than Anakin was when the dark side came a-callin'. Though they did share similar attachments (Anakin's visions of Padme dying in childbirth; Luke's visions of his friends being tortured on Cloud City), Luke wanted to fight for good for the sake of fighting for good, because that's what his father did, because Luke is selfless; while Anakin wanted to save Padme at the cost of everything else. In the end, his drive to do good and save her brought only evil and cost him her life, as well (this is why Lucas calls the story a "Tragedy") because Anakin is selfish.

Luke was always the epitome of the optimistic, incorruptible hero; whereas Anakin was the tragic figure who was doomed to fall, if you look at them from an "archetype" standpoint.