The best bottom feeding or something to keep substrate clean would be a nice water change, gravel vac and a great maintenance routine
Wit that said I do have a pleco, feather fin and a synodontis along with 4 botia loaches in my 75 gallon African cichlid tank.
Now to answer your original question since its gone a little off topic.
Decor is personal preference. Things they will need, hiding places and areas to call there's little areas of territory. Rocks are good as some are rock dwellers. Stack them and make more caves.
I've always said to try and leave the front of the tank open for free swim and stack everything to the back.
I went a little out of the norm you could say. I love the of driftwood in a tank. This is why I say it's what you like. You have to stare at it not us.
But those things I mentioned are things that will help your fish out. If one is stressed or being picked on or even holding they can find a cave or little area to call there own.
Here's my tank. 75 gallon heavily stocked mixed African cichlid tank.