On Wednesday night, Washington Performing Arts Society opened its fall classical music season with a spectacular concert by the La Scala Philharmonic. Notably it did so not at the Kennedy Center, which has long been the organization’s main venue, but at the newer and growing Music Center at Strathmore. In spite of the suburban location, which doubled this disgruntled city dweller’s car trip, a VIP box at house left held such distinguished guests as First…