Eitan C.
Koh Chang has plenty to do: beaches, cooking classes, good restaurants, hotels at all price levels, diving shops, waterfalls, day trips, and viewpoints all over the island. We preferred the southern beaches, though that's down to taste. Kai Bae felt central to us and close to Bang Bai pier for diving and boat tours, as well as some lovely beaches. I'd recommend renting a scooter for flexibility, and taking a day trip by scooter to Koh Ngam and the southernmost beaches. The ride to the edge of the island is worth it.

