I have searched the forum but can't find a definitive answer:

I am a US Citizen and I will be going to Penang and want a 90 day Non-Immigrant Visa O for purposes of retirement (That I intend extend here in Thailand with all the required documentation).

What supporting documentation do I need?

There is no set requirement other than being over age 50. Proof of 800k in bank account is sometimes asked but most times a single entry is available without.

Do you need to go out of country? If you meet the requirements for retirement extension of stay you can obtain without leaving as the non immigrant visa entry can be obtained from immigration for 2,000 baht.

Are you going to use the monthly income or the 800,000baht in bank you may need proof of this. The Embassy in Laos wanted a guy I met last year to have the money in a Thai bank and because he didn't have it wouldn't give him the non-o. But Penang maybe different but go prepared. Remember if you cannot get the non-o you can convert a tourist visa at immigration to a non-o and then get your extension

My assumption was that the Consulate in Penang would issue a initial Single Entry 90Day Non-Immigration O (NOT an O-A) Visa without requiring any income or bank info.

All the proof of income & bank info would have to be provided when I eventually go to Thai Immigration to ask for the 1 year extension of stay...

Do you need to book a appointment or can you just turn up and get one, I need the multi O based on Marriage ,any one recommend a good hotel I could stay