I have heared that some seo expert use to do this tatic for keyword analysing. First use to take keywords from google keyword tool and sort it then put that keyword in google insight if it is good searchable keyword only they will take or else search other one.. for good sorting we have to use this google isght also
Both of those search options have different type of results. Yes you are right google insight are advanced method of searching keyword by geographic location also keywords movers & shakers option is the better one there.
I suggest you don't worry about Keywords or the Density of KWs etc: We need to write quality content for our site visitors and KWs will come in the content naturally:
Should choose some related and close toeach other keywords and then come up with unique and quality content by mixing that all selected keywords and in this way you will get the maximum benefit of both insight & research tools.
Yes you do need quality content, but when writing your content it is always best to do keyword search first and add these keywords to your content. Keyword search helps you get targeted content by finding out what people are searching for and what keywords they are using to get to your content. The correct keywords will also help speed up the process for google ranking, and the higher the rank the more visitors you will get