Chicago -- Tim Roby, a senior marketing executive for the Atlantis resort in the Bahamas, yesterday was named president of the Chicago Convention and Tourism Bureau.Roby will take over the bureau's top staff position on April 3. He replaces Chris Bowers, who resigned last August.Roby will not assume Bowers's title, chief executive, which has been eliminated. The bureau's former president--the then number two position--was previously held by Deborah Sexton, who quit the bureau about a year ago to head up the Professional Convention Management Association."We're fortunate to have someone with Tim's strong sales and marketing track record and impressive credentials," said Phil Stefani, bureau chairman and president of Phil Stefani Signature Restaurants.Roby has served as senior vice president of sales and marketing for Kerzner International Resorts. He was primarily responsible for marketing Atlantis Paradise Island, a massive property containing 2,300 guest rooms, 35 restaurants and bars, a casino, and a yacht marina.Prior to his tenure at Kerzner, Roby served as senior vice president of sales at another huge resort, the 5,005-room MGM Grand Hotel and Casino, in Las Vegas.Roby started his hospitality career in 1983 as convention services floor manager at the Hyatt Regency Minneapolis. He worked at Hyatt for 13 years, progressing to director of sales and marketing at Hyatt properties in Texas and California.Bill Utter, who led the bureau on an interim basis while the search for a new president was conducted, will return to his position as the bureau's vice president of marketing.