Today I've tried to open a bank account at 3 different banks in Hua Hin to no avail.
I'm on a DTV Visa and I've got a Certificate of Residence (and got my Thai driving licence with it) but none of this was of any interest to the banks. Every bank asked me for my passport only and once they saw the DTV stamp they declined my request. KBank, Krungsri and Bangkok Bank. So alas a DTV + COR is by no means a guarantee for getting a bank account atm.