I've had good luck with gold dust plecos (Baryancistrus xanthellus, L-081) in a mixed Vieja tank. They feed on algae and help keep the rocks, but not glass, clean. Avoid Royal Plecos (Panaque spp) and similar because they feed on wood and produce incredible amounts of waste.
More generally, I think you are better off with an excellent filtration than bottom feeders. Cichlids root around in the gravel for food anyway, so I think the more efficient clean up strategy would be a strong mechanical filtration system and vacuuming the substrate when needed. Not that you shouldn't get any bottom feeders, but I would do so because you like their addition to the tank rather than for their clean-up capacity. Given the appetites of cichlids, you may find yourself adding additional food at night just so your catfish get enough!