Depends on the purpose of the doorway and the areas it connects. If it's a main route that will be frequented by players, a wider door such in the range of 192-256 HU would be good (sometimes even wider). If it's an infrequently used door along a minor flank route, a smaller door of 128-160 HU width may be more optimal.
The size of a door can somewhat influence how players behave around it, but at the same time the size of a door should complement, not contradict, the way players are trying to use it.