Bay seniors who’ve overcome their prejudices against ranch house architecture have a chance this Saturday to visit one of the jewels of that style – The Frank Lloyd Wright designed Buehler House in Orinda. Built in 1948 in a style Wright called Usonian (for USA. He thought “American” was too broad a term) that featured flat roofs and as much light as possible.He put gold leaf in the living room ceiling to reflect more sunshine. The Japanese garden was created by Henry Matusantani, responsible for SF’s Tea Gardens. The event is this Saturday July 30 from 10 to 5. The tour is $50. A wine reception at 6:30 is an additional $75, benefiting the Frank Lloyd Wright Building Conservancy.