NAI Sullivan Group, an Oklahoma City-based commercial real estate firm, has appointed Nicole Mayes, David Hartnack and Sam Swanson to vice presidents of their divisions. Mayes will lead the office team while Hartnack and Swanson will head the company’s retail sector. Specializing in marketing, relationship management, negotiations and problem solving, Mayes brings more than 10 years of experience to her role. Bringing more than seven years of experience, Hartnack specializes in helping real estate owners turn around troubled retail centers and purchase and acquire quality investments. Swanson holds over six years of experience in Oklahoma City and Tulsa commercial real estate. With a specialty in contract negotiations, retail site selection and analysis, leasing, and investment sales, Swanson has earned the distinction of one of the leading retail sales and leasing brokers in the Oklahoma real estate market.