In my opinion, the health insurance industry is regulated to heavily favor industry rather than consumers. If you are older and retired, it's probably best to plan on self insuring.
There are also very good government hospitals that offer after hours clinics for very reasonable prices. In essence, they function like a private hospital during evening hours. Ramathibodi and Chula are good examples of this. I'm registered and seek health care at both places. Not difficult to do...and a good deal.