We are still hesitating between going to Phuket or Koh Chang. What would you recommend for a family with 2 young kids? And if any one can recommend a nice hotel (around 200 dollars) with good snorkelling around , that does not look like it was built out of concrete and cement to accomodate 500 tourists, I will appreciate.

Well you won't find any 500 room hotel blocks on Koh Chang, well, not yet anyway.

The islands are totally different, also they are affected by different climate zones.

May to October Gulf od Thailand area has the best weather ( Koh Chang, Koh Samet, Jomtien beach, Pattaya, Cha Am, Hua hin, Pranburi, Koh Tao, Koh Phangan, Koh Samui )

Although some parts of the Gulf have decent weather almost year round if you are looking at November thru April for the south then Krabi, Phuket, Phi Phi, Koh Lanta, Trang area is a dry time of year.

Phuket is highly developed, malls, lots of tours, lots of restaurants, entertainment, shows, Phuket Fantasea, etc etc, Koh Chang is a much more relaxed and laid back place, perhaps Phuket 20 ys back sort of thing.

You need to decide first time of year choice re-weather and then whether you want a busy place or a very quiet island.

If you want a busy island beach place May to October then Samui with kids would fit the bill.

USD 200 even if for 4 of you is a good wide open budget, you can find places that can sleep 2 adults and 2 kids, but first we need to know time of year and whether you want a busy or quieter place.

Just to add there is snorkeling from both places, from Koh Chang around the protected sea national park, from Phuket around offshore islands and also around Phi Phi.