If here often it may be best to open a bank account in Thailand and either bring in or transfer money to it. I use my Thai ATM regularly without and fees.

At one point when I was needing money from home, I would do a cash advance from my Visa card over the counter (ant Thai bank). I could withdraw/access up to my card's limit (several hundred thousand Baht) instantly and without a fee. Then I would immediately pay off my Visa card via Internet banking.
No fees. No interest.

I understand convenience, but why pay so much in fees just to access your own money??????