Several offices have moved in recent years, but are still on maps or traffic signs in the old locations. Old and new locations given where I know. In addition, some are on wrong location in google maps (corrections submitted).
I will visit more and take pictures, finally can call the post: Pictorial guide to TAT offices in Thailand (there are some abroad as well).
Some are in houses obviously erected for being a TAT office, some in interesting architectural styles, others in nondescript buildings.
See here as well:
List alphabetically by their English name (Phra Nakhon Si Ayutthaya filed as Ayutthaya), data from http://www.tatnews.org/tat-local-offices/ slightly edited.
3. TAT Chachoengsao Office
I have been to the temporary office.
6. TAT Chumphon Office
7. TAT Hat Yai Office
I have been in Jan 2015 but didn't take picture.
I have been, but can't find the pictures.
สำนักศิลปากรที่ 4 ลพบุรี The 4th regional office of fine arts Lopburi, and moved to 14.799985, 100.651173 = 14°47'60.0"N 100°39'04.2"E on the grounds of Lopburi City Hall ศาลากลางจังหวัดลพบุรี (NW corner of Narai Traffic circle).
I have seen it driving past on bus.
18. TAT Nakhon Si Thammarat Office
I have been in Aug 2014 but didn't take pictures.
Hwy 4084, southern side, out of town directly after the bridge.
20. TAT Pattaya Office
I have been many times, and taking another picture next time I go is faster than searching for pictures I took in the past.
I have been in Aug 2015 but didn't take pictures.
(I took frontal pictures from middle of road on another visit, just can't find it!)
28. TAT Samut Songkhram Office
32. TAT Surin Office
33. TAT Tak Office
35. TAT Trat Office
36. TAT Ubon Ratchathani Office
37. TAT Udon Thani Office
38. TAT Uthai Thani Office