Tourist visa will easily get you 90 days. 60 plus 30 day extension.
Currently the STV gets you 90 days and can be renewed 2x equally 9 months.
However it cannot to modified to another visa or extended any longer. You have to leave when it is done. Extensions are straight forward for visas, 1900b lots of photo copied stuff, no need for an agent.
By your post you will have 90 day non-o based on retirement when you arrive and spouse will be non-o based on being married to you. (Must be done before you arrive, otherwise the spouse will have to leave and reenter)
I am in phuket and each office can have different rules, but we were able to do our one year extensions at the same time. Required only a photo copy of our marriage certificate, not translated or notarized.
It was actually very simple except for many copies needed of:
Passport pages- EXTRAS of husbands to attach to her file.
Tm30
Current bank statement- do a transaction that day and update
They also made me copy all pages of my bank book
Bank letter no more than 7 days old
Stamped and picked up the next day, 1900b each.
You may need to go to the local immigration and ask to be sure.