Thanks! Helpful suggestions

We use window units for a couple hours before bed, then fans

You can adjust how open the vents are on each floor. Open them wide on the hot floor and close them a bit on the colder floor. Not a miracle cure but should help.

Our 3-floor 1900ish rowhouse has central A/C. Yet the degree differential on each floor is probably 10 degrees, so a freezing basement with blazing hot bedrooms. We rent, so we can't make major modifications, but any ideas for moving the air around a bit more (and saving us $ on a/c)? Thanks!