I haven't lived on any island for long, hence our upcoming big adventure (starts this summer). I have lived on the coasts of Florida for many years and spent time on many Florida barrier islands, the Keys, the Caymans, the Bahamas, and even some Canadian islands in the Great Lakes!
But from anywhere in the Caribbean you can get to Miami, or anywhere on the East Coast in a day or less. From Culebra, it's a puddle jumper to San Juan and then 3 hours to Miami. From Panama's islands it is a similar puddle jump, and there are many directs right into Houston and other airports.
The challenges I've seen are getting TO the Caribbean islands from anywhere NOT on the East Coast. The flights from west (I live in Colorado) don't get to the East Coast in time for the departing flights to the islands. So you either do a red-eye, or an overnight stay on the East Coast. Both suck.
As for medical care, I believe San Juan PR has good care, and Panama is noted for good doctors and hospitals. I'm sure there are others with decent care (Florida isn't exactly noted as having world class health care BTW). A big part of our "plan" is that we live there in our 50s and 60s, but then back in the states around 70 and beyond when our needs are greater. Plan is in quotes because it isn't really a plan...