The single largest vacant office space in Downtown San Jose is Legacy Partner's massive tower at 300 Park Avenue, which is 320,000 SQFT. Much like the Sobrato Tower, Legacy has been holding out for a single tenant for the whole building. It is much easier to manage one tenant as opposed to several smaller tenants, and the location of this tower would make a great corporate headquarters for a large company like Adobe.
However, it looks like the strategy of looking for a single tenant has not panned out so well. Legacy is now leasing the building floor by floor. The results? They now have three letters of intent to move into the building.
Source: SVBJ, Thanks Jonathan Bush for the tip!