We have no experience in Asia but here are some suggestions.
Use Visa or another credit card (for credit, not cash withdrawals) for purchases as often as possible.
Check out RBC’s VIP plan. About $35 per month gets you no fee withdrawals at ATMs on the Plus network. Find out whether it’s in Thailand. Neither end (RBC nor the ATM) charges a fee. We’ve used it extensively in Europe and recently in Colombia. It’s preferable to Visa as there’s no interest charged on what you withdraw.
There can be maximums on what you can withdraw per day, so plan for large transactions like rent.
Manage your funds across accounts and pay your credit cards online.
If you go with RBC and your ATM card is declined twice for any reason, do not use it again for 24 hours. RBC said that with the third decline in24 hours it can be blocked and can only be unblocked onsite at an RBC location in Canada. That’s when your Visa card as backup for cash withdrawals would be needed.
Travel with cards for two separate Visa accounts so that if one is lost, or gets shut down you have the other. Never carry them both on your person unless there’s no other choice. If you each have a card for each account, when carrying them all, each person should carry both cards for one account so the other account isn’t affected if one person loses them or is robbed.
When buying on credit, if the machine offers for you to pay in your currency or the local one, common agreement is to select local, so that your credit card company determines the exchange rate and not the vendors bank or credit card provider.
Hope that helps.