If you want fair, then as Cath notes you can't select based upon exotic places as most of us don't live in such a location nor can we afford to travel to such a location.
Fairness would also eliminate awarding a Tee based upon the most prolific producer of threads since someone such as me, who is retired, would have plenty of time to do so.
You might want to consider having several categories of posts in which a Tee is awarded. For example:
January: Most humorous pond experience post(s)
February: Most informative pond construction post(s)
March: Most helpful member post(s)
April: Most informative pond plant post(s)
May: Best greeter of new members post(s)
June: Best pond photo post(s)
July: Best pond fish photo post(s)
August: Random drawing
September: Mikey month
etc.............................................