When you land in Bangkok, just after the passport control you will be able to withdraw money with your VISA credit card (see my post about the DB credit card: I just got 20’000 Baht and no DKB fees. Only 150 Baht for the ATM).
Don’t lose time as I did, looking for an international bank to avoid the 150 Baht fee. I asked and a guy at the airport told me that there is no ATM without fees, at the airport. In the city you may find the AEON bank or other international banks, but not at the airport.
So, if you need money, just go to the first ATM you find and withdraw 15’000 Baht or 20’000 or entering your custom amount and that’s it.
Update: I kept all the reseeds for all the withdrawals (I took a picture with the phone) and at the end of the trip I sent an e-mail to DKB. DKB refunded me all the ATM fees. The DKB-Cash Visa credit card is just awesome!