A number of our Presidents, including some of our best ones, have never had executive experience as an elected official.
(You can debate whether things like being a military officer, directing a large political campaign or Congressional staff, running a private business, or even running a volunteer organization or voter registration project "count" as "executive experience," but Palin's supporters seem to be elevating elected office above those sorts of experience in handling budgets, overseeing and directing staff, and making strategy decisions.)

But given the responsibilites and duties of our Chief Executive -- which include making major decisions affecting foreign relations, the interior, labor and business relations, internal and international economy, and upholding the US Constitution -- I think any unbiased observer would say that experience on the NATIONAL and INTERNATIONAL scene is at least as important as having prior elected office as an executive. Not all our Presidents have had military experience, not all have studied or practiced law - much less, Constitutional Law, not all have legislative experience, not all have lived or traveled abroad or had to deal much with foreign relations, and not all have held elected political office.   
I guess, other things being equal, the ideal candidate would have all those qualifications, but none of our "top 4" does this year.   
~McCain has military experience.
~McCain and Biden have the longest government experience.
~McCain, Biden, and Obama all have 4 years or more national governmental experience.
~Palin and Biden both have governmental executive experience (Biden served on the County Council of Newcastle Co., Delaware).
~Biden, McCain, and Obama all have experience living or travelling in countries outside North America and have experience dealing with foreign relations issues as Senators.
~Biden and Obama both have law degrees and have studied and taught Constitutional Law.

Considering all this, how can anyone seriously say that Palin places anywhere but at the bottom of the list when it comes to the kinds of experience and education that would give you the skills AND KNOWLEDGE/UNDERSTANDING important to being our nation's Chief Executive?

Sure, you can be briefed on where various countries are and who their current leaders are, maybe even get a crash course in key areas of international conflict.   But a few weeks or months of coaching will not compensate for having been involved in decision-making at the national and international level for several years or more.

Palin's focus over the past decade has been - perhaps rightly - on "What's best for Alaska?" Not sure how well that's prepared her for shifting to "What's best for the USA?"

Yes, we have had state Governors who've become President, and some have done a very good job. But the successful ones have pretty much all either been Governor of a big state with a politically diverse population (e.g., New York, Ohio, or California), had substantial military experience, and/or had law degrees and experience.