I spent one week at Chaweng this summer with my family (wife and 7yr old son). We stayed at the Chaweng Regent Beach Resort on the main strip which we found to be a very nice place although a bit pricy.
Most days were spent relaxing on the beach or by the pool and exploring the restaurants and attractions along the main strip at night. We also had one day with Samui Explorer visiting the following sights around the island:
Big Buddha Temple
Grandfather Grandmother Rocks
We found the guide extremely friendly and knowledgeable (Mr Nong) and we learnt a lot, not only about the sights, but also about Thailand in general. The only slightly negative thing was that the program we had been given beforehand by the company was too much to fit into the 5 hours that the trip lasted so we had to skip some sights.
I have summed it all up in a 4K video that might be useful for first timers to the island. It includes an overview of Chaweng (Beach, Main Street, Food, Nightlife) as well as the sights from our trip with Samui Explorer: “KO SAMUI – The Essential – Beach, Food, Sights, Nightlife”: https://youtu.be/xS90uPMHo3M