To start the ball rolling, some suggestions, trying to use existing tags where possible:
floor-plan already exists on 5 questions and can be used for the distribution of chairs & tables.
data-visualization already exists on 228 questions and can be used for the layout of data on a screen.
user-interface already exists on 80 questions and can be used for the layout of web forms etc on screen.
desktop-publishing already exists on 11 questions and can be used for the layout of information on a printed page.
gardening and landscape already exist on 3 and 4 questions respectively (some questions have both tags) and can be used for the layout of gardens of all sizes.
For questions about layout of components on PCBs, I don't believe the existing electronics tag is specific enough. So, I would suggest creating pcb-design.
Many of the, now 30, questions with layout-designer also have the above suggestions as tags. So, retagging would be quite a painless process.