AJALT are the people who publish the Japanese for Busy People books, so if you like those books you might want to investigate their Japanese language classes. After some investigation, I have heard that their classes are good but are geared more toward executive learners. This means that the class size is small and the lessons are provided in smaller doses with less homework.
I investigated quite a few Japanese language classes in Tokyo. I heard some recommendations for the Japanese Language Institute (Nichibei Kawai Gakuin) in Yotsuya. I heard that this school is very good for conversation and quite reasonable for the price. However, apparently the workload is heavy and if you get behind in class, there is no remedial help to get you back on track.
In Tokyo, I started with an excellent one-month intensive course at MLC. I like their blurb:
I was living in Sydney before I moved to Tokyo. Apart from a lot of self-study, I enrolled in a night school Japanese language course run by the University of Sydney. It was a nice gentle introduction to Japanese, and good practice in speaking and listening to a native speaker. But I wouldn’t recommend doing this for more than about ten classes.
Here’s an excellent description of what it’s really like to study this fascinating language. This piece was written by Dan Barrett, a student at an American college. The original website has now disappeared, so I have preserved his article here.