I took dollars, although the exchanges in Yangon airport did also take euros. Make sure all notes are uncreased and in pristine condition. As I was doing the add on, I changed 150 dollars for kyat (pronounced chat) on arrival in Yangon. I paid for a couple of meals on the main tour in dollars, and after buying a few souvenirs, I still had some kyat left which I used to part pay my bill at the beach hotel. For anyone doing the add on, the hotel does take credit cards, but adds a 3% surcharge to card payments. I don't think anyone in my group used an atm, but there were money change facilities at all of the airports we used for internal flights. Hope that helps.
