The opinion on Yellow Tangs has somewhat changed, and has been debated here for some time. From what I understand now, a tank with a 4 ft - footprint will do OK. Typically, that is no less than a 50-55g tank. Of course, the larger the better.
The reason is that they need space to dart back and forth.
Kole Tangs stay the smallest out of all of them, so perhaps that is the way to go.