Run HVAC fan throughout the day for comfort
Continuous fan operation equalizes temperature and humidity between different areas of the home, and particularly between levels (where convection results in higher upstairs temperatures). It's also the case that even minor airflow helps a person feel cooler by enhancing evaporation on the skin. It's a good practice to reduce cooling costs because the compressor won't need to run as much for a given comfort level. 

Sure, there's some wear to the fan bearings incurred, but fan startup is hard on the fan, so there's benefit from fewer startup cycles as well. I don't see how fan speed is particularly important except with respect to noise, should that be a concern.