Neither East nor West
The Iranians are the only people in the world who successfully defended themselves when their country was invaded by an enemy equipped with Soviet hardware and backed by all the major Western powers. These are people to be reckoned with!
The Iranians paid dearly for their independence, and they will not give it up and submit themselves to the domination of the US-led multinational empire easily.
Still Very Much Rebellious
Qaddafi didn't come into power through social revolution, like the one that convulsed Iran from bottom up. Instead, he won state power through a bloodless coup d'état. It's easier for Washington to deal with a dictator who rules the passive population, whether to depose him (as in Iraq) or work with him (as in Libya), than with the collectivist leadership who lead the historically revolutionary and still very much politically active population like Iran's.
Let's say Washington offers a deal, and Khamenei, et al. take it. Washington can't rule out that the people of Iran won't, sooner or later, undo it, either restoring the status quo ante or even taking their revolution to a new, higher stage.
Washington's enemy is not Khamenei or Rafsanjani, or even Ahmadinejad -- its enemy is the people of Iran.
Britsh MPs visiting the Pentagon to discuss America's stance on Iran and Iraq were shocked to be told by one of President Bush's senior women officials [Debra Cagan, Deputy Assistant Secretary for Coalition Affairs to Defence Secretary Robert Gates]: "I hate all Iranians." (Simon Walters, "I Hate All Iranians, US Aide Tells MPs," Daily Mail, 29 September 2007)