Here at the university we often joke that things go so much better once the students leave. This is partially true -- parking is easy to find, lunchtime lines are smaller, and since there are no classes to prepare for, many professors can devote most of their time to research.
But if pressed, I would admit that I doubt more work gets done. Due to the lack of classroom responsibilities in the summer, the summer months tend to be when most astronomical conferences are held. At the present, my supervisor and one office mate are at a month-long workshop in Aspen, Colorado, and my other office mate is meeting collaborators in Hawaii. A couple of weeks ago, the summer meeting of the American Astronomical Society was held in Calgary. I will be traveling to England in early August for a meeting dealing with white dwarfs (my research), and the triennial meeting of the International Astronomical Union will be held in Prague in mid-August. And this is just a small sampling of the meetings this summer.
So, due to these meetings, my office and the hallways are very quiet, almost eerily so. It is nice to have the office to myself, though!