For retirement options, you can refer to the attachment as a very summarised comparison. Three from the left are popular options in this group.
Also, Multiple entry Non-O immigrant based on pensioner visa is available at only some embassies, not everywhere. This visa is valid for 1 year, giving you 90 days on every entry. But most likely you need to apply this in your home country. Check them about this.
Another option might be METV, which is valid for 6 months, 60 days every entry.
If you are in Thailand, maybe the <Non-O acquired inside Thailand option in the attached picture+following 1-year extension+re-entry permit for each stamp> might be reasonable.
As in the attachment, you can apply for Non-O retirement in Thailand if you meet the requirements. Those requirements are immigration office-specific, go to your local immigration office to get the handout of requirements. You may be able to check the website of your local immigration office.
Here is general information for in-country Non-O retirement.
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/9.FOR-RETIREMENT-PURPOSES-50-YEARS-OLD-NON-O.pdf