If you are both Non Thai's then you will need to show 800,000 each and possibly some to cover the Children too, if one of you is retirement age then it's possible to get a retirement visa showing just 800k the other partner could get a student visa to learn Thai and when that finishes ( usually 6 months) then 'follow' the retirement visa holder with a dependant visa.
Krungsri (yellow bank) or Kasikorn are better banks and you will need a residence certificate form from immigration to be able to open one. good idea to have several passport sized pics to hand, you will need them.