Looking southeast across the lobby from the entrance portico--the photo that I took on October 25, 2012.
Looking that same direction in a photo taken in 1977 when Durham & Bates occupied the building.
Here's a bit about the upper floors of the Bank of California building, from the 1978 application to the National Register of Historic Places:
As previously mentioned, a new entrance was installed to provide access to the elevator lobby serving the upper floor tenant spaces. This lobby was formed by partitioning off a portion of the space under the mezzanine at the north end of the banking room.
The second and third floors, previously used as administrative offices and work spaces for the bank, will soon be available as rental offices. The second floor boasts a 13' high ceiling--higher than is offered by most modern tenant spaces being built today. Aside from this, the space is not unusual. It is planned to update this floor with the installation of air conditioning units above a new acoustical ceiling, carpeting, lighting and partitioning to suit tenant requirements.
The third floor, having a usable area somewhat smaller than the second floor, is housed beneath the hipped, tile roof. This provides a low plate height along the west and south walls and sloped ceilings which extend up to the east-facing windows and clerestory, giving a unique garrett-like appearance to the space. This floor was originally used as a lounge, library, and recreation space for the bank's employees.