This book has an excellent overview of living overseas listed by country. The book is probably worth it for the country-by-country section alone. From Central to South America, then Europe, then Asia, you get an overview of life outside the US and budgets for retirees. Healthcare is discussed, along with insurance issues (some places won't issue a policy after age 64) and whether or not the healthcare system is a good one.
There is a also a discussion of lifestyle--I wish there had been more, for some of the countries where the authors have lived. They moved around a lot. They offer advice such as bringing your American appliances as buying them overseas can be terribly expensive and they are not as good--but there is little discussion of the fact you may have to pay duty, in many places on personal items brought in. There are a lot of import tariffs you may not expect. Is is better to hire a laundry service or simply deal with foreign appliances? And what about voltages? Yes, you can use a step-down transformer in countries with 220V, but 50Hz vs 60Hz is tough on motors, so often, it's not practical. But..this is just one aspect of living overseas.
There is also a chapter on working overseas, teaching, volunteering. It's a sketchy discussion but the bottom line is "don't rely on extra income from working."
A bigger issue: What does "good healthcare" actually mean? If you are ill, really ill, you'd possibly need to come to the US for treatment for very serious problems such as cancer or advanced cardiac surgery. That's where the rest of the world comes when the chips are really down. Yes, our system has many problems, but American medicine is outstanding for complicated illness. I am not convinced this is true for other countries necessarily. A lot has to do with where the teaching hospitals are--because this is generally where the most advanced medicine is available. So if you face a life-threatening illness, are you willing or able to take up temporary residence back in the US, in a city where your particular illness can be treated? That's a serious consideration. Or will you have access to the most advanced, life-saving treatments in your country of residence?
The advice on local languages may be true up to a point--yes, a thriving ex-pat community means you may not have to acquire fluency. And yes, many countries teach English and locals use it as well as their own language. Legal lingo in any language is complex and idiomatic. If you have a problem understanding form letters from tax or financial institutions in the US, it will be a lot worse in any foreign language, even if you are pretty good. You'll need a local advisor of some sort--someone trustworthy. And if some event or disaster is going down where you live (Nicaragua has earthquakes, for example and some of the tropical Caribbean nations experience severe hurricanes) are you going to be able to listen and understand notifications and get timely emergency advice? Where do you go in an emergency? What if it's chaotic?
And that brings me to the final issue that I thought was touched on by the authors: you are leaving your natural support network. Many people grow up in and stay and work in the same region their entire life. When you leave, you leave family, children, relatives, business people you know and trust. You will have to build a support network where you move to--and the authors write that they moved more than a few times. As we get older, this gets more difficult.
I thought the authors did a good job touching on each issue and listing budgets, lifestyle and pros and cons of living in various overseas areas. You'd need more than this book to thoroughly research where you might like to live in retirement if it's outside the US. Each person's situation is different. This is no small project, but "The International Guide" is a great place to start.