Businesses are making Louisville, Ky., a laboratory for marketing to the over-65 set. An "experience center," at 18,000 square feet, is scheduled to open there next year. It will be a place where startups and other companies can demonstrate and test new products for seniors. InnovateLTC is the organization behind this project. The idea is that the center, kind of a mall for seniors' products, will draw consumers and industry leaders from across the country.