As a monarchist, I view von Stauffenburg, like the majority of the German officers who sided with the Nazis, as traitors to their rightful sovereign. I can somewhat admire people like von Bock, Canaris, and Beck, who quit when the Nazis were very much winning and because they didn't like the warcrimes they were seeing, but Stauffenburg? He was an opportunist, and he was a traitor to his Kaiser, but not to Hitler, as that implies he owed any form of loyalty to Hitler.
As a student of this period your appraisal is quite thought provoking, especially as one considers the alternatives in time.
As to the July 20 Plot my opinion is that it was desperation and at least to some a necessary if hopeless act to show the Allies that Germans were not a monolithic enemy or Nazis, in that vein the "heroism" was the suicidal attempt and how it in hindsight served to exonerate the Wehrmacht and buy a better peace, or at least I feel it has been bootstrapped and made the myth. To the post-war era their treason is a bright spot of resistance shined to a high polish. In fairness it is not meant as insult but perhaps a more sober view of history and its complexity.