When setting up a new tank, consider it a blank canvas. This means you can do whatever you want. In fact, use your imagination…or no imagination at all. It’s easy to construct your cichlids’ new environment from the bottom up, but consider going the opposite direction. Start from the surface and work down. How much open water in the top column do you want? You know the height of the your tank and you know where the water line should be. Do you want decorations or plants that reach the surface? Do you want the mid-level water to be open or occupied too?
If you like to create the normal way, from the bottom up, don’t be homogenous with the substrate. Nothing dictates that you must use a single substrate. I’ve had tanks with both gravel and sand. They’re awesome. The tank doesn’t need to be symmetrical either. Mix it up. Obviously, the larger (e.g., longer) the tank, the more options you have to make the environment a composite. Use one type of rock on one end and use another type on the other end. Maybe create a step-down environment – make your rock-work higher on one end and step down to nothing on the other to mimic shoreline. If you have a SA/CA tank, put rocks on one end and wood on the other. Use multiple types of wood, different lengths, different thicknesses.
If you’re looking for a true biotope display, nature is rarely symmetrical. Don’t make the tank look like someone set it up. To get ideas, look at some photos of the lake bottom of your fishes’ endemic environment. And keep this in mind; your fish don’t care. As long as you provide sufficient cover for any fish that need it, use your imagination or just put stuff in at random. No one is going to see the tank more than you (and anyone else that lives with you). You should enjoy looking at it and watching your fish.