Prepping for a hellish summer- window ac or a split air conditioning system to supplement the home ac system?

So last summer we had monster electricity bills like everyone else and have taken care of getting better insulation, plantation shutters etc. Our ac is also in decent working condition and not due for replacement for another 2-3 years.

I have friends that keep their home temperature high in peak summer (85 f or so) and cool their primary spaces like the bedrooms with either a window ac or a mini split air conditioner. The split apparently cools very well and takes little energy and is a highly recommended option.

Does anyone have any experience with either? Any pros and cons to these systems? Also, how are you prepping your homes for the upcoming intense summer heat?