I am going to let you all into a little secret...
For years the coastline between Deia and Valldemossa for me offered the best view of the Mallorcan sunset, especially Sa Foradada. Sa Foradada is breathtaking with views overlooking a little rocky peninsula and the wide Mediterranean Sea. Over the years word has spread and it has become very busy there during high season. The DJ sessions they have at the weekends have an amazing vibe.
However, if you are looking for a more peaceful way to watch the sun go down, there is an Arabic tower on top of a hill in George Sand, near Valldemossa, that offers the most breathtaking views across the coastline and out to the sea.
Shhhhh... it's a hidden peaceful gem, let's keep it to ourselves!