Tenants have the upper hand in New York as landlords contend with a record number of empty storefronts. : In the area around the Plaza Hotel on Fifth Avenue, home to the borough’s priciest retail real estate, rents fell 13.5 percent in the second quarter from the previous three months, the largest decline among the 16 neighborhoods tracked by brokerage CBRE Group Inc. The drop was due in part to a single space that had its price cut from $3,500 a square foot to $2,500, CBRE said in a report Tuesday.