I tried the new Isolate Shadows function to see how it works. I think the results are quite nice. The objects receive light and shadows from all light sources but are not casting shadows to other objects.
I just expected it to work a bit different. I expected we have a menu like for changing materials but with the option to select from models. The disadvantage now is that when you change the object you always also will reset the camera position. Would it be possible to move this control from the menu of the upper right (also) to a menu located at the object itself? And keep the current camera position?
Anyway, I tried to fo find a way to add the missing shadow below those objects. I created a plane object and added a map with a soft shadow texture and transparent borders. This is not a very accurate way but it helps to give the impression that it casts shadows and is part of the scene.
Here you can see the results (Sofa 3 with and without the helper shadow)
isolate shadows test