You won't convince any CCs with data about incarceration in state prisons, since they do not have to foot those costs, and MMJ patients are not prosecuted. Stick to things that affect their bottom line. If you bring crime into your presentation, they'll harden. Instead, concentrate on the economic benefits, and try to find some good examples of other similar towns or counties who have good regulations. The only things the CC cares about are the cost to the county and the reaction of their constituents. If you can show them that MMJ will benefit your county and that commercial growing will not impact the community (i.e. cause neighbors to complain) you should do well.

FYI, make an appointment with the county planner and hear what he has to say before you go before the commission. If you can anticipate some of the commission's objections, you will be more convincing.

EDIT: If any of your surrounding counties have MMJ regs, you should get a copy of them to bring to the CC. They will be inclined to follow the herd.