cichlids w/plecos
I have plecos with my Discus. I kept them w/ Angels too. The key is to get a decent sized pleco to start with. You must also give the pleco a cave or flower pot to live in, he will then defend his small area.
There are only a very few varieties called "common" plecos. There are sOOO many more fancy ones. Some prefer gravel/sand bottom tanks, but most REQUIRE a piece of real driftwood in the tank. Plecos EAT driftwood and will not do well without it. Also, a pleco can starve to death if the fish above him eat all the food on the way down, or if other bottom dwellers are faster than him(cory cats, synos...).
Currently in my discus tank I have:
Green Phantom pleco
Chocolate Zebras 2
Yellow King Tiger
Clown Pleco- baby
Snowball Pleco
Chocolate Pleco(sailfin)