The roundup of convention ideas is here.
Most conventions that have pro-fan panels have workshops, from cosplay, to writing, to graphics. These are well-loved and well-recieved and a great way to impart serious knowledge in a fun situation.
Stocking a good workshop is hard as, simply, you have to find people that know how to run them and know what they're talking about. For small conventions, or ones adding more pro-fan panels you may want to add more workshops, but you're not sure how to get the people to do them.