@Gail ******
the Non O is easier then the OA. You can apply before you leave Canada, the requirements are fairly easy to meet. You'll get stamped in for 90 days and can then apply for the yearly extension. When we did it we only needed the insurance requirement for the 90 days so we used a CAD company for that.
Bring a proof of income statement with you, you get the copy from CRA based on your last tax return. Once here, you go to the Canadian Consulate in Chiang Mai or Embassy in BKK and get an affidavit of income. If married, you can also get them to certify your marriage license so that one of you can be a "trailing spouse" so only one person has to show they meet the minimum financials. Then go to immigration with the letter and all other documents, pay 1900THB and get a year extension based on retirement. It was really easy to do. Currently there is no insurance requirement for the extension so you can get whatever insurance locally whenever you are ready for it.
We were able to use our Non O to open a bank account within the first month of arrival. While we didn't need it for immigration, it does make day to day transactions easier.