If the room is a rectangle with the entry door on one end, try putting two bookcases together back to back with their side against the room’s wall, making a divider wall. No coat closet, put an armoire and bookcase back to back or even two armoires. Just make sure both units are the same height and width. There’s great ‘unassembled furniture’ available at a low cost, and many different styles. If you haven’t looked, you might be surprised at how much better the quality is today.
*** For stability, bolt them together, back to back in a way that they can easily be disassembled without damage. The next place you live may be a different room arrangement, and they can be used in another way.
If the living room is small, try using cases that are table height to keep the area open. Put a table runner on top, and that will hide the seam, then decorate the top with a few items as if it were a sofa table. A lamp would be nice on the end next to the room’s wall—instant light when entering the room. Just make sure to keep the lamp in proportion to the bookcases, and the shade isn’t bigger than the width of the cases. You don’t want anyone brushing against the lamp, and knocking it off. A rectangle shaped shade would work great.
If you use bookcases with solid doors, this will also provide extra storage for shoes, mittens, scarves, and other things that you want to hide; two great functions from a clever decorating idea. Remember, think outside the box!