You do not want to miss this. We were lucky to be the only two individuals chosen from the standby list on the day we flew over Bagan. The experience is as cerebral as it is exhilarating. The company that operates Balloons Over Bagan makes the experience completely safe (they have an excellent record and reputation). I would recommend reserving a spot 6 months in advance if you can plan that far ahead (it's ~$300 a person, and worth every penny). As you can imagine, this is a rightfully popular activity in Bagan.