We use a split system in our open plan lounge, dining and kitchen. It blows directly down the passage to the bedrooms and that stops them getting too hot.
Plus ds1 and dd's bedroom has got the carport and fence right outside so that keeps the sun off. Ds2's bedroom gets the morning sun and the aircon blows directly down there.
We leave the aircon on most of the night and I'll turn it off for a bit in the morning.