If ventilation will be adeqate for your needs, then I suggest an exhaust fan mounted in the roof or gable. You can put vents in the ceilings of the closets.
The fan will exhaust the attic which will help reduce the heat transfer to the upstairs rooms, and will draw outside air through open windows.
The fan in the roof will be barely heard in the house. There is usually a temperature switch that causes the fan to operate when the attic is warm. You could have a circuit with controls that would permit you to operate it with the temperature switch or manually.