The following is a first hand report of an Expat extending his permission to stay based on being married to a Thai at Chonburi (Pattaya) Immigration:

I recently did a successful extension of stay based on marriage to Thai.  This extension does has a few more steps than a retirement extension, and will require BOTH parties attending immigration.  (not an agent friendly task, as you have to go anyways)

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I will confirm that since I had arrived on an e-visa, immigration wanted copy of emailed e-visa.

I will confirm they wanted photos of myself with the wife.  My error was in printing in Black & White.  We had to reprint them in color, two copies.   They asked for photos in front of address at house,  in living room,  in kitchen and  in bedroom.  

I will confirm they wanted 400,000 baht proof from bank, seasoned two months.   This required visit to bank for letter of balance and history.  Same as extension of stay based on retirement, except different aged amount.   (I think they will also accept 40,000 monthly, but can not confirm)

I will confirm immigration wanted copy of Blue Housebook (Thai citizen).  I had also provided copy of Yellow Housebook (foreigner). It was accepted but I do not think required. 

I will confirm since we had been married in Thailand, we presented copy of Thai Marriage certificate.  (this is the form with a colored border with heart on the bottom)  And we had to visit (in our case) the Banglamung district amphor for certificate we were still married.  I think it was called Thor Tor 2.   This was an easy process that they were aware of at Banglamung.   My understanding is that this is required each year. 

I will confirm that officers WILL VISIT YOUR HOME, and you will need to have someone (Thai) present with ID & Housebook to vouch for you.  Speaking to neighbors who have been on marriage extension, they have visited every year for the past six.   A hand drawn map is asked for.   Basically officers just need to fill in forms your witness signs.

Then once the forms, plus application,are submitted they stamped passport with 30 day extension.  I kept the passport.  Then "WE" returned to immigration to have one year extension stamped, once Bangkok had approved.