Like the title says it would be nice if the medium and large houses had a customizable sound that played when a guest entered. This could get annoying if people come in and out so maybe put a delay between when it plays. The sound also does not need to be super loud, more like a gentle tone.
Customization could be different sounds from in-game like just a standard bell, the sound the chocobos make or one of the many other sounds or noises the game has to offer.