Speaking of attics, last year we not only had extra blown-in insulation added (to R-50) but before that we had heat barrier reflective film (think Space Blanket) installed to the roof rafters. We also replaced the 110v roof fan with a solar unit (If it's sunnin' it's runnin'!)
Holy smoke what a difference! Instead of the usual 130-150° up there in the summer, it now barely gets above ambient. That means MUCH less heat for the insulation to block.
Thirdly, we had the exterior walls filled with non-expanding water-based foam. Outside sound was cut by at least half, and the inside walls stay cool to the touch all day - and night.
Yesterday, although it hit 100°, our Air Con unit didn't come on until after 3 pm with the thermostat set at 75°. The house just doesn't heat up, period.
