Will leaving my ceiling fan on all the time, even if no one is in the room, help reduce my overall A/C expense?

No, a ceiling fan will not save energy if no one is in the room. Ceiling fans do not actually lower the temperature of a room. They make us feel cooler by moving air over our skin, which increases evaporation of the moisture on our skin. Instead of running your AC at 72 degrees, a fan allows you to set your thermostat to 78, yet still feel as if it is about six degrees cooler. A fan costs pennies per day to operate versus dollars per day for the AC.