[LazyPup]

Typically we make the waist arm at 16" to 18" unless there is a specific reason such as a deep sink, on the other hand, the code will allow the tailpiece from the sink to be a maximum of 24" vertical from the elevation of the drain opening to the water level in the trap. In most instances 14" would be adequate for a deep sink, but i would measure the cabinet height, deduct the sink depth then deduct another 6" or even more if there is going to be a disposal on the deep sink.