I like this site/list better:
http://www.countyfairgrounds.net/iowa/iowa.php
The targeting is a little short sighted here. There are 2 targets: The Straw Poll which just gets us electability creds nationwide and the PRIMARY which is what really counts! We won't have another chance to reach this many people before the primary, this easily again.
Ranking by cost would be another way to look at things.
In general:
The bigger the fair, the longer it runs and the more expensive booth space is.
Bigger fairs sell out of booth space sooner. Sometimes you can strike a deal with a political party or the RNC to share booth space if it's sold out - we did this last time.
Staffing is one of the biggest problems.
While we are at it, one of the best ways to get access to PRIMARY voters is a week after the straw poll. I'm referring to putting up a table during orientation week on college and university campuses. Sometimes you have to be an exiting on campus organization to do this, and sometimes not.
-t