To me, the single biggest thing that I look for in a President is the ability to surround himself with good people whom he can trust to make solid decisions for him. As much as the POTUS guides policy, his aides are the ones that shape this policy. Unfortunately, we don't get to vote on an entire Cabinet.
At this time, we've truly seen one major decision made by each POTUS candidate. In some ways, the VP serves in an advisory role - and I subscribe to the theory that the VP should help fill a void in the POTUS's resume. Let's take a look at this from my left-leaning glasses:
OBAMA: Greatest weakness is a perceived lack of experience, particularly in the areas of Foreign Policy and National Security.
Choice: A long-term Senator familiar with the ins and outs of government, currently the leading figure in Foreign Relations in the legislative branch of the government, and a well-respected man.
MCCAIN: Greatest weakness is a perceived notion that he is a same-old same-old of the last 8 years.
Choice: A virtual unknown with no Washington experience in any capacity; some experience with change at the state level.
From that view, i don't think she was the WORST McCain could have done, but we'll have to see if they can frame their ticket as a team as well as Obama-Biden did this week - that'll be the key to me.