I would fight to have your employer let you bring your bike inside. You will become overly familiar with freight elevators, but when your bike is sitting next to your desk all day, it's not going to get stolen.
If you're talking about trips in addition to the commute to the office, the considerations really depend on the location. The sturdier the lock the better, but in many cases, a superior lock out of view could be considered worse security than a lesser lock with more eyes on.
You'd be well-advised to secure, in addition to the frame, components like wheels and seat, especially if they're quick release. For that, a lighter cable (maybe even one with a built-in combo lock) might suffice as deterrent, but again, it depends. Some of our opportunistic friends seem to be more interested in wheels than frames.