If you want space to set up food, the basement might actually be a better space for you. I think we can fit 100 people in the Basement Hall and you would be able to set up projectors, power, table, chairs, food, etc.
One thing I'm not sure you're entirely clear on, though, is that it wouldn't be an event in sudo room -- sudo room's new location is in the Omni Commons, which is a collective of collective. Both the basement and the ballroom are common spaces. that's not to say that sudo room wouldn't be involved, but it does mean that the best way to go about seeing if the hackathon could be hosted at the Omni is to set up a booking request.