You said it yourself: There can be no general recipe. That's true for any 3D program. If the beauty pass looks decent enough, then there is no need to export the separate shading components, but at the same time if you export one like Specular or Diffuse, you have to export them all most likely and reassemble the shot, using the beauty pass as a guide only. That ultimately is the whole point. of course there's any number of inbetweens like using a specular pass and boosting it to create over-exposure effects or feeding it into glows. In the end it all depends, but you should quickly forget meaningless generic terms like "decent look" and "standard set". At the end of the day you can crank out all those passes and if you compose them in the wrong way, it will still look garbage...
It's all about the layers and the blend modes and what you want or need to do in the shot in post. The must have combination may be as simple as only adding a shadow pass or it may require every pass your software is capable of rendering. Try and make your best guess as to what you may want to edit or change to color correct and grade the final images then export those and start playing around.
Thank you gents, I appreciate your input and advice!