The first time Matt White walked through the office building that most folks know as the Harrah's parking garage, he was distracted by an aging motel building to the east.If White's Basin Street Properties bought the building 145,000 square feet of office space and 950 parking spaces he figured that his company's efforts to upgrade the building would need to overcome the image problem presented by the motel."The existing uses on the site next door presented a lot of challenges to us," he said last week.The answer for the Petaluma, Calif., real estate company? Buy the motel and another neighboring …