Check out the EIR for the building:
http://sacrbr.aecomonline.net/ceqa.htm . It's worth a read--if you want to skip the boring stuff, look at Chapters 2 and 3, the executive summary and project description.
Currently, the plan is to leave the Heilbron mansion in place, restore it, and make it into the centerpiece of a public plaza for the new building. The cry to save the mansion was huge, and included both city and state electeds. City officials might not make much to the state, but Assembly/Senate members do, and they stood up to this. I'm not expecting great artistry from the state for this building, but it will be nice to see something besides a parking lot there, with the mansion as its centerpiece. The building has been a restaurant, a bank, and an art gallery--who knows what else it could be in this new plan?
Sure, the BOE building was terrible, but the 1980s were not a good time for architecture.
A surprising number of those 1960s parking lots (1950s was when the City knocked down the neighborhood on Capitol Avenue west of 7th, the state knocked down the stuff south of the Capitol a decade later) have turned into other things--CADA has built more than a thousand new units of housing, in addition to office properties, and has more plans for some of those parking lots in the near future. In fact, they recently acquired their first new property in a long time, behind Safeway on 18th, and CFY just submitted their plans to the city to build a midrise building with more than 150 apartments including 40% affordable housing units.