Snap grid (regulable to 5, 10 cm...)
I don't believe in a snap to the grid function. Measure walls around you, you'll see that it's unrealistic, their length are never a multiple of 5 or 10. But a better magnetism system would be really helpful, for example to arrange cabinets side by side.
Change type design wall (inter axis quote is not useful to interior design)
This is a very old suggestion but as soon as you want to draw multiple rooms, I didn't find any better solution yet. If you have to design only one room, draw it with the room creation tool then choose the wall creation tool and double click in the room to create the walls around it.Copy style wall
There's a plugin for that but I'm not sure it works that well. 
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Emmanuel Puybaret, Sweet Home 3D creator
