I hate Phuket but lived in Nai Harn not Patong. Phuket is expensive, infested witrh Russians and the natural habitat other than the beaches has largely been detroyed for tourism. I suspect you have a reason for living there and after 27 years you are probably nicely set up there. For a relative newcomer looking for somewhere to live out the last years of life, it's not a place I would advise him to move to. In fact out of the three places mentioned, I'd choose Bangkok, but I am sure he could find somewhere much more leisurely and affordable elsewhere in the country. Phuket is also the one place in Thailand in which your own transport is an absolute necessity. At 76, you don't want to be negotiating for a fair price with the local transport mafia.
Glai and glai for two things that mean the total opposite really irks me when I am trying to establish distances. Sitting in a restaurant ordering food and not having the waiter understand 'kaou' is another pet hate.
Off subject, but the dog park within Benjakitti was very disappointing and not a place in which I would bother walking dogs unless I lived next door. Concrete paths between impenetrable vegetation and filthy, smelly water, all in a very confined area. No off lead area but no shortage of officious notices.
I understand very well your desire to live in Thailand versus the USA. If you have a 2 bedroom apartment with pool in Thailand you are obviously not on the poverty line. I am in a similar position as a 70 year old here who also has to make a decision to forsake the safety of a free healthcare system to take my chances with a system for which I would have to pay. It's not the 'dying prematurely' bit that worries me. It's having a stroke or heart attack in a foreign country and spending a huge chunk of my capital on hospital and medical care, while having no local personal support. Dying quickly whether prematurely or not would be the preferred outcome.