I've been there before. It's such a beautiful place. The beaches on the island are fine and soft, and the sea water is extremely clear. It's so pleasant to soak up the sun and enjoy the sea breeze by the sea. Besides, there are lots of local specialties there, such as Tom Yum Goong and Som Tam. They all taste really great.
If you go there, you can book a hotel by the sea online in advance. Then you can enjoy the wonderful sea view as soon as you open your eyes every morning. For transportation, it's quite interesting to rent a scooter and travel around the island. You can freely visit various fun places and check in. I hope you'll have a wonderful time on Koh Samui!