I think one thing to take seriously before taking a class is how much the teaching reflects the kind of Q you do. For instance, I plan to take the Plowboys/ Butchers class primarily to get some tips on how to get the most out of the FEC. If you cook with a stickburner at high temps them maybe a class taught by Mike Davis or Myron Mixon would be better for you. In addition some classes give you a look into the complete cooking process (rubs, injections and everything else). Some will only give you help on techniques - but they won't give you specific help on flavors etc.
So, what do you need/expect to learn?