I like Sarah Palin. Selecting her as running mate was a bold move and paid initial dividends. There could more payoff from that pick in the coming weeks - particularly after the VP debate.
Given the current economic crisis, however; a Mitt Romney pick could have turned a perceived McCain weakness into a major strength for the ticket. Romney has the proven financial expertise that no one else on either ticket possesses. With him on the ticket, McCain could have gone to the bailout bill negotiations with some real substance (provided by Romney) to inject into the discussion. He could even put forth his campaign's own plan to resolve the crisis, and be taken much more seriously in this current debate.
Hindsight is 20/20, but there were certainly signs of pending financial doom in August and a Romney pick would have just made sense. With Romney on the economy and McCain on foreign policy, imagine the possibilities.
I don't believe in shaking up the ticket now, but a formal announcement of Romney as chief financial advisor to the campaign would play well. Maybe drop some hints of a treasury secretary appointment in the McCain Administration. One way or another. McCain should reach out to him. What does he have to lose at this point?