Phuket or Ko Samui With Children

Hi,
I'm just starting to look into this and my basic question is this: For you seasoned travelers, do you think it would work well to take a 4 and 6 year old to Thailand? Some
concerns aside of the flight are eating (non spicy foods) or getting sick over there with young kids. Plus the haul from the West coast of the USA all the way to Phuket.
We're primarily looking for a beach vacation and kicked around Vietnam and Bali but Thailand seems easiest to get to. We'd stay in 4/5 star places. The kids have been to Europe but that's the farthest. Do you guys have any insight or advice as to one place (Phuket/Ko Samui, Krabi or even Vietnam) over another? Your thoughts are
appreciated. Thanks!

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I personally like Kohchang, as it's off the normal touristy stuff, and more quiet, but it costs a bit more. Western food is everywhere so the kids should be fine. My 1st trip to Thailand was a few decades ago as a child with no issues except for all the vaccinations updates prior per my father at the age of 5.

http://iamkohchang.com/

I consider Samui to be the ass end of Thailand... very overrated, more expensive than the mainland and id say 99% of the westerners who live there are ex crims on the run...

just my opinion based on experiences