Mike @ OtherSide in Islamorada
http://www.othersideboardsports.com/

Amazing location for learning, flat & shallow. Great instructor, reasonable rate.

Here's a pic of my girlfriend taking a class

Uh, sorry to disappoint, but your beginner friends will not be able to ride at Matheson. There is a kite school van there that only allows IKO3 to kite with a ribbon. Beginners have to take a class with the school. Same story at North Beach in Key Biscayne, IKO3 or school. you can check with schools...