Using google analytics for refining a blog until you make the first conversion?
 

Things don't convert like they used to, we all know that. But the time between when a blog affiliate first converts can be a while.
Is google analytics the best way to go on spreading it across your wordpress multisite to see what retains and see what blog styles get the best responses?

Or how would you go about this....

You could have phrased your question better, however if you're asking which analytics you should use the my advice is to use Piwik if you can.

Stay away as much as you can from Google Analytics... I know why I say this... don't believe me? Ok, try it for your own, dude.