I have updated an article on this very subject - it now comes with a checklist to use when looking at venues to hire. Covers about 100 different questions or things to think about before putting down your hard-earned cash on a venue. It's mostly about seasons, rather than touring or outdoor events, but should cover some of the latter anyway.

Download the list via:

http://www.schoolofpuppetry.com.au/tutorials.php/how-to-choose-the-right-venue-for-your-show