Pleasants Development Monday announced its plans to build Mount Airy Crossing, a mixed-use community that will offer a blend of senior housing, single-family homes and boutique shopping and dining options, along with more than 25 acres of parks and open space. The proposed development reflects substantial changes made in response to feedback received during a three-day public design charrette that Pleasants Development hosted in late May on its plan to develop a 91-acre tract of land along Route 27 into a vibrant mixed-use neighborhood.