+1 on uaru fitting the bill you're describing. Not always the showiest fish in terms of color, more impressive in size, peaceful behavior, etc. But there is an orange type-- will not get into some debate on taxononmy, nomenclature, etc. --but what some call a sp. orange. Not always easy to find, though.
I've seen H. psittacus go both ways-- other people's tanks, yet to keep them myself. Have seen adult parrots be just fine with discus, severums, peaceful geos, but also heard of them getting nasty.
On another note, I've kept severum (rotkeil) and angelfish (Peruvian scalare) together and they paid little attention to each other for the most part. Not as likely to work in a smallish tank, and may not work with the occasional nasty severum-- which ime usually has a lot to do with the sev feeling crowded, I've taken on literal killer sevs that were just fine in a larger tank after I got them. But from my experience, it can be done with rotkeils with no problem at all with sufficient tank space.
Beyond cichlids, have you considered arowana, stingray, or some of the larger fancy plecos?
I've seen H. psittacus go both ways-- other people's tanks, yet to keep them myself. Have seen adult parrots be just fine with discus, severums, peaceful geos, but also heard of them getting nasty.
On another note, I've kept severum (rotkeil) and angelfish (Peruvian scalare) together and they paid little attention to each other for the most part. Not as likely to work in a smallish tank, and may not work with the occasional nasty severum-- which ime usually has a lot to do with the sev feeling crowded, I've taken on literal killer sevs that were just fine in a larger tank after I got them. But from my experience, it can be done with rotkeils with no problem at all with sufficient tank space.
Beyond cichlids, have you considered arowana, stingray, or some of the larger fancy plecos?