Go for a holiday and travel around the regions you are thinking of.
Personally I love Malaysia, Thailand, Bali, etc but I am happy living anywhere that is warm and by the sea.
If you need your creature comforts US style or have specific health issues then these need to be taken into consideration.
Australia might be another good option, Ningalo reef might meet be worth a look, it does not have to be the great barrier reef.
A friend of mine bought an RV in Australia and drove around for 6 months 2 years running (returning to the UK for summers) and had a great time. Sold the RV with very little loss. My brother did something similar in the USA.
Have fun and keep us updated on your research