Well, the past few days have been nice and cool outside, but before that, it was pretty warm around here. I've found that a few air circulators (in the real world, we call these fans) make a dramatic difference in cooling efficiency. My house is great at cooling the downstairs, but there's not much airflow to the upstairs, so it was still staying fairly toasty even with the A/C on. It was better than before the heat pump, but not necessarily good enough to justify the many thousands of dollars I spent to cool it. Now I have a fan bringing cold air from downstairs to the second floor, and all is well. The only drawback is that now I have a fan in my stairwell. I imagine that this will only be necessary for the hottest couple of months each year, but it's hard to tell at this point. I'll need to come up with some creative solution for next summer.
Next time I buy a place, in the distant future, I will make sure that the house was designed for air conditioning. It's still hard for me to grasp that air conditioning is not common here, so ventilation systems are designed lazily and do not support it well.