Most of the tourist books say the top things to do in Koh Chang is to sunbath. When the weather is good you can literally lie on the beach until it gets to hot and then either jump into the sea or grab a drink.
Even though the development of attractions is as much as the usual Thai beaches there is plenty more things to do on a Koh Chang. Up the south coast of the Island, each bay and beach area has its own feel. A mentioned we stayed at Lonely beach ( which is a backpackers haven) but we ventured out on scooters to go down South, but grabbing a taxi to go North- as the roads started to get a bit difficult for beginners!)
Wondering through shops or to the waterfalls are great days out, which can be done in most places on the Island. We tried out renting kayaks for a couple of hours to venture to our own secluded island or paradise.