I did a quick video on 3 different meditation retreat options in Thailand for visitors, you can find it below:
Someone compiled a PDF of information for 40 different meditation retreats in Thailand, Burma, Sri Lanka, India, and Nepal. Some of the information is outdated, as this was compiled in 2010. Still, you can gain useful information for it about retreats in Asia. The links to all the Thailand meditation retreats are here:
Thailand Meditation Retreats listed here >
40 Meditation Retreats – Thailand, Burma, Nepal, India, Sri Lanka