Well, you might be surprised but much of South America has rather solid health care. In fact, many have universal healthcare coverage (as well as free college education...but now we're really opening a can of worms).

It depends on how large of a city you'd want. Lima, Peru is always overlooked by tourists, but it has the best food on the continent, is on the ocean, and has some of the friendliest people.

Colombia has a number of options for living close to the mountains as well as being by the water. If health care is a major concern I would recommend remaining somewhat close to a larger city though. Medellin isn't on the water, but I think it's one of the most beautiful cities on the continent (I'd move there if they allowed my dog).

I have less knowledge about the Brazilian healthcare system, but there are a number of fantastic cities on the coastline not named Rio. Rio gets most of the tourists, while the other beach towns remain mostly subdued (outside of maybe locals coming in for the day).

Google "Arraial do Cabo" it's a smaller town in Brazil. Maybe 30K people. Closer to Rio so it's easy enough to fly to. An option, but there are many little towns like this in Brazil and Colombia.