Bangkok is a good place for aerobics dancing. Many places in Bangkok, for example, supermarkets or public parks, offer free outdoor aerobics classes. These classes usually start in the morning at 06:00 or in the evening at 18:00, and the session would last for one hour. Wear appropriate clothing. These classes don't require Thai language skill because instructor rarely uses verbal cues. Aside from exercising you can also meet the community of local people and foreigners.
For supermarkets, you can expect to find classes in Lotus or Big C. They only have classes in the evening, and are usually held in or nearby the parking areas. For public parks, there are many places but the most famous one is in the Lumphini park in Silom district. They have classes in the morning and in the evening at the ceremonial gate.