Did they have a plasma before? The "grainy cinematic look" comment sounds like a plasma owner.

You are doing right by specifying OLED as a replacement, although it will look its best in a darker room or if you can control light levels in the room with drapes or shades.

The Sony OLEDs are a slight step up from the LGs (IMO), with the Sony video processing making the difference, but both are at the top of the TV food chain.