Off the top of my head, I can tell you that Wheeler's main auditorium holds 760 people; after the closure of the U.C. Theatre, local film festivals began holding their Berkeley screenings there. So, this is a very large building housing many large lecture hall classes and dozens of discussion sections; you rob banks because that's where the money is and you take over Wheeler Hall because that's the way to make the biggest impression on fellow students and the media.
So that makes Wheeler one of the most favorable buildings to seize whenever students wish to make a statement. In 2002, pro-Palestinian demonstrators took over the hall; ubiquitous protester Roberto Hernandez was accused of biting a police officer (he was acquitted). Last year, two men occupied a tree outside Wheeler. Classes were disrupted during affirmative action protests in the 1990s, and the building was occupied by anti-Apartheid demonstrators in the 1970s.
A quick glance at the above also reveals that while seizing Wheeler gets attention, it almost always doesn't get you what you want (and, when those causes prevailed, it took decades). Sadly enough, one could argue which is the more hopeless cause: peace in the Middle East or solvency in California and affordable college tuition for excellent public universities.
Good luck, students.
Photo | Berkeley Architectural Heritage Association