I like the coupe cases, nice an open for cooling. My Pi 4B is in a black one. My 3A+'s are all in coupe cases too. The Pi 4 runs hot, I have a fan shim on mine.
There are lots of PiTFT displays out there that plug into and use the GPIO to drive them. If you go that route I would use a booster header to raise it up to let air in under it to cool the Pi 4.
The Hyperpixel display works via the GPIO and has a nice resolution, it will interfere with the fan shim though as it uses pretty well every GPIO pin and refunctions most of them for special use. You could go with a heatsink instead of the Fan Shim. The Pi 4 will never overheat, but it will down clock the CPU to reduce heat if it starts to get hot. That will impact performance.