The way I would set up the AP is to take your office space, break it in half, and then find the center of each space and that would be the area that you should put the AP and depending on the amount of walls that it has to go through, all of your clients should be able to get the signal. You also mighht want to raise the router higher so that the signal will go out further in your office space.
If you are covering over 100 personnel, you might want to consider using four AP’s, two in each area, and created a vlan for each area, then you would break the office area into quarters. You would get better coverage that way.
Hope this helps.