Multi-player Gliding

I was thinking of having a multi-player gliding night and started to ask myself a few questions.
I remember as a boy when i lived in Huntly (yes, i know!), i would go up with my parents and see the gliders flying around Meremere. Does anybody know where they take off from? EDIT: Waharoa Airfield
Then i got to thinking, where else could we have a gliding session together. Do you know of any places that are famous and well known for gliding?
Since i have never relly tried out the gliding i also started to think about the thermals. Are they only in the Missions or are the thermals placed everywhere or only in prefered gliding areas?