Often rooms in offices & many other spaces involve clusters of objects one might want to move in one go (e.g. a table with 8 chairs). Would be wonderful to have the option to select and manipulate multiple objects at once. Could be with Shift+Click (select multiple) or a marquee selector (select all in area).
Actions possible with multiple objects would be drag to move; copy/cut and paste; and also Del to delete (the latter should come with a warning).
(Taking it one step further, you could borrow interface logic from illustration tools and allow grouping multiple items into a "group object" treated as a single thing; but none of that is required for the above to work and make many users happy.)