Just extended my 60 day tourist visa at CW in BKK. Went in the afternoon and it took a mere 50 minutes. Only problem I had was they wouldn't accept my photograph (be sure to remove your glasses if you normally wear them). Currently no request for TM30s there. However, this IS definitely required by the immigration at Pattaya-Jomtiem. You must take along a print-out of the hotel's online registration in order to get a TM30 receipt BEFORE you can submit a TM7 there. Be aware that lots of smaller hotels and guesthouses won't automatically register you, either because they can't be bothered, or because they are wanting to stay off the government system (e.g. to avoid tax).
TLDR : Answer Summary
The user successfully extended their 60 day tourist visa at Chaengwattana Immigration Office in Bangkok, completing the process in about 50 minutes. They noted that wearing glasses in the photograph was a problem and advised that TM30 registration is not required at this location. However, a TM30 receipt is necessary in Pattaya-Jomtien, where proof of hotel registration must be presented before submitting a TM7 form.