D.C. Mayor Vincent C. Gray (D) and his economic development team have selected a group led by Hines Interests, of Houston, to oversee efforts to transform the former Walter Reed Army Medical Center in Washington into a 3 million-square-foot town center project. With a proposal called “The Parks at Walter Reed,” Hines and partners Urban Atlantic and Triden Development won the endorsement of both community groups and Victor Hoskins, deputy mayor for planning and economic development, who said Hines offered the District the best deal and a vision that most coincided with its own.