It would be really nice if "Show other objects while in groups" worked not only with objects that have been grouped with the Group command but also with objects like roofs and floors. It is inconvenient to edit a floor and not be able to snap to the walls.
The only way I have figured out to do it is to draw a rectangle, copy it, enter the group, paste in place, edit the floor, erase the rectangle and exit the group. Not a very big problem but it seems to have uneccessary steps.