The fact that many responders have not been asked is irrelevant to the fact that an individual entering on a tourism entry stamp can be asked to show the equivalent of 20,000B cash, that's the law.
You qualify for a Non-O based on Marriage or Retirement, both can be applied for before travelling to Thailand and will give you 90 days on entry. You then apply for a 12 month Extension of Stay (cost 1900B) based on the reason the Non-O was issued by meeting the Thai banked asmount requirement. A re-entry permit cost single 1000B or multi 3800B) allows you to keep your 12 month status live while travelling outside of Thailand.