Don't count on a communal office as security. Any unlocked bike is at a high risk of being stolen, no matter where it is or how many people are around it.

Don't park the bike in the same place every time, because then the thieves will know the pattern and be able to determine the best time/method to steal it. They can optimize their technique to get that one bike at a particular time. Most schools have an ample supply of bike racks on campus, use a different one each time and just walk an extra block or two every now & then.

Stop by the campus police department and ask them where the most bikes have been stolen from and avoid those locations. Odds are it will be all over the place though, because most students don't know much about bike security and buy cheap, department store cable locks that are easily defeated. Depending on school policy, you may have to register the bike with them anyway so if that's the case, it wouldn't hurt to ask.

Another general rule of bike security is to never leave your bike outside overnight, even if it is locked.

To help your search for a specific product, many companies rate their locks in terms of how much security they provide. Kryptonite is one. Personally, I have no problems whatsoever with the extra weight of a stronger lock or chain, because I'd rather carry the extra weight and have the bike waiting for me when I go back outside, than carry a lightweight lock and find out later that my bike was stolen. This is one area where it does not pay to be a weight-weenie.