Richard Brennan runs an exceptional Alexander Technique training course in Ireland. One of its distinguishing features is week-long visits by teachers of international reputation.
The Society of Teachers of the Alexander Technique was founded in 1958 and is the largest such organisation in the world. This website includes a directory of members.
Robert Rickover practices Alexander Technique in Nebraska and Canada. He has also built this incredible online resource. The audio section alone has hundreds of interviews about the Technique.