I am finishing 2 bedrooms, a bathroom, and a landing area in my basement. I will be adding another heat vent in the bathroom and one of the rooms. The other areas already have heat vents in the ceiling from the original construction. My question is: Do I need cold air vents in all or none of the rooms, or will one central vent work. The area is only about 620 square ft. My thought, and obviously the easiest, was to go up into the cold air return duct already existing in the ceiling, and locate it centrally in the hallway area close to all areas. What do you think? I might mention, our basement has always been comfortable, either warm or cool, with all the vents closed, so extreme temperatures are not an issue. Thanks!

A central high return like you are talking about will work as long as the doors have some clearance at the bottom so the return air can flow under the door to the hallway.