Phuket viewpoints are plenty, and to find a good Phuket viewpoint is not hard, one could simply follow the western beach roads from north to south, and easily spot several great views, teriffic seaview and wonderfull viewpoints of Phuket.
The Phuket island view is great as the landscape has been formed for centuries to what can give you an amazing view of Phuket. There is several location that will give you amazing sunsets view, but an perfect sunset would mostly depend on the weather and the clouds, even if a sunset on a beach overlooking the calm sea is probably helping to create that tropical feeling.
If you start in the north and drive down the west cost, you find some of those famous spot, there is really no need for a viewpoint map here, you will know once you pass a good viewpoint, and you might even discover a few new viewpoints, even if most of the comon viewpoints starts from patong and down to phromthep cape.
Drive on just a bit futher to the south, you will find Phromthep Cape, the most visited sunset viewpoint in Phuket, you will find it quite well visited during the hour near the time for a sunset view.
Viewpoints are best visited during the day, and some during the sunset hour.