I think that's the problem with Tony's issues. He's self-destructing because he's dying and not by his own choices. Now, he is choosing to act this way because he is dying. But a more compelling reason would have been if he just couldn't handle the success, his ego, his problems with the government, a legitimate threat from Hammer, and just turned to drinking and bad choices as an alternative. But his dying (a weak storyline because it will eventually be fixed) is the reason for his behavior.
Another issue I had was everyone talking about how Tony had brought world peace but not seeing any of it. It was completely off-camera. We don't get to see Tony as the hero except for the two battles against Whiplash.
^Stane was a great villain, particularly the way Jeff Bridges played him in the 1st movie. He had an interesting rapport with Tony when they were friends. He clearly had a certain appreciation for Tony's genius even if he was exasperated at having to cover for a bunch of Tony's messes. Then, when we find out he's a bad guy, he's hella scary. I especially love the scene with Pepper in Stane's office. Even though very little is happening in that scene, the tension is quite palpable.
Yeah, Stane's issues and relationship with Tony is something that really worked in the film. They tried to establish a connection between Vanko and Stark with Vanko's father having worked and helped Stark. But it was a connection that never felt very strong. So there's really not an effective personal issue between the two. Spider-Man at least had strong personal issues with all of his villains in the movie. Sandman killing Uncle Ben was was complete and utter dogshit but at least Tobey Maguire sold Peter's hatred for him.