First, Geithner never worked at or for Goldman. Factually inaccurate, though widely believed in Internet chatter.
Second, AIG was a mistake, although Geithner won't admit it. In the press of the crisis, there was the belief that if all contracts with all counterparties were not honored, it would start a run on the derivatives market that would bring the whole system down. This wasn't designed to "save" Goldman or any other particular counterparty. It was to prevent a run on the system. The concern was very legitimate. But if they had taken a few more hours or days to address the AIG problem and thought it through a bit more, they could have crafted a solution that would not have given every creditor and counterparty 100 cents on the dollar. People make mistakes -- get over it.
That said, in exchange for the 100 cents, the US government now owns assets that, in fact, have appreciated in value more than anticipated, so the "cost" of the AIG bailout will turn out to be less than first thought.
As for the auto creditors getting less than 100 cents, that was a different matter that did not involve trying to prevent a financial meltdown. That was an industrial bailout. There was a good reason for it, considering the state of the economy, but it did not require giving all creditors 100 cents on the dollar.
This isn't about fairness. Sorry about that, but it just isn't. It is about solving very real, very pressing and urgent, economic and financial system problems in a way that costs the least amount of money to the taxpayer and causes the least distortion to the markets and the economy. There are lots of things in life that are unfair, and this is one of them.