Im no expert on health coverage and insurance so please take my advice with that in mind. To my knowledge, currently the following companies in the area offer weight loss. Many offer the lap band and RNY. Few extend their weight loss surgery options to include the Verticle Sleeve which is the surgery procedure I'm set on. I would start investigating with the three companies I have listed below as to my understanding, they offer the most choices in terms of procdures available to you.
United Health Care
I would encourage you to browse through the Wisconsin sub forum here and read up on people's feedback on their insurance approval.