San Francisco gave Bobby Weir one more glorious Saturday. Exactly a week after his death , some 20,000 Deadheads and other fans, along with family and many friends, gathered at the Civic Center Plaza, just across Polk Street from City Hall, and across Grove Street to the Bill Graham Civic Auditorium. They convened after many of them had walked, in his honor, up the city’s main boulevard,  Market Street, to the Plaza. The organizers of the memorial celebration announced that there would be no