Hi,
If you are looking for used furniture you can try in najma old and new furniture souq.
For show pieces and paintings you can try AL-RAWNAQ and AL-RAMEEZ CENTER. You have verity of showpieces, home decoration stuff, stationery, kitchen utensils, bathroom stuff (like shower curtains, scented dry flowers, bathroom mats etc...)These stores are located on airport
These above stores are very reasonable and not much expensive. If you are looking for branded expensive, stuff you can go home center, homes r us.

Enjoy shopping my friend