I'm in the process of doing the reverse. I have a house where all the ceiling lights have been changed to ceiling fans with no light kits. Walking into a room at night was a problem. I have solved this several ways. In the guest room, i dropped another 14/2 wire down the wall, converted the wall switch box to a double, and added another switch leg for an existing outlet. This now switches a table lamp besides the bed.
In the master bed room, and after a not so fun experience with removing a single and installing a double gang box, repairing the plaster, etc, I dropped a second wire down to the existing switch box, installed a combination fan/light switch, and now the top operates the fan and the bottom switches an outlet by the bed. (Not the one with the alarm clock)
In both these cases, I was able to locate the wire going down the wall from the attic. I cut into the wire, added a junction box, and ran a switched leg back to the wall switch.
In the dining/living room, I left the whole fan and its switch alone and picked up power from another existing junction box, added a new ceiling box, installed a small chandelier, dropped a wire down a different wall and installed a wall dimmer switch.
Most electrical codes require that you have the ability to light a room from a wall switch as you enter it. As always, learn the electrical codes and design and install by them. They make sense and encorage safety.