I imagine an easy way to do the picture, that is all the members sitted at a long table, looking at the camera, with the chairman in the center, as if they were on a press conference or presiding a big meeting. The background can have flags and/or pictures on the wall, portraits, logos, or anything else related to the corporation.
A second way is, as you said, surrounding a round table. This option is more difficult, because the sense of reality is affected by the different light sources used when the individual pictures were taken. But in Photoshop, I can shade or enlighten different sides of the faces, in order to give the sensation that all members were illuminated by the same light source simultaneously, as if they were together when the fake group picture was taken. I have done something similar, and it worked.