I pitched an Iron Man 2 rewrite where we learn at the end of the film that Mandarin has been secretly behind the scenes and manipulating things since the first film. In my version he is responsible for the stuff with the Senate and Justin Hammer wanting his own Stark Tech because it sets up the Armor Wars. It's been a while since I came up with it but forgot the bulk of the details. Tasha was Shield plant sent by Fury to watch Stark and make sure he doesn't get out of control. Bethany Cabe had an increased role as Stark's budding new love interest.
I agree with Dream's statement regarding the real villain being Tony's drinking problem with I think was handled great in the film. Whiplash and Hammer were surface villains.