Tankmates for angelfish?

Well I have 2 Angelfish that are inseperable- they are a pair but not breeding. In the other tank they have been in they were extremely peaceful. I have just re-located them to a new 90 gallon that has cycled for 7 weeks and has a bristlenose pleco. I am wary of putting other new angels in there, for I am afraid they may fight. I am looking for a middle-dwelling unique fish that mature around the same size as full-grown angels, or get a little bigger. The fish also has to be pretty peaceful. Any creative ideas?