Yeah i agree with rocks and driftwood. i think most of us do the rock thing as caves are essential to create a natural habitat.
i found that in south and central american tanks, mostly driftwood looks the best. Not only does the wood make cool shapes and caves, but the water can stain a slightly yellow colour which i think looks cool with them !
Africans on the other hand look awesome and prefer rocks with most of the tank (or all) made of caves. It gives them places to hide, make their own territory and to breed in too
Hope that helped a tad