Brazilian grammas look cool. They are similar to the royal gramma, but the colors blend together more making them look better IMO.
I had a flame angel in my old 55g FOWLR tank and loved it. If you are not keeping corals, then this or a coral beauty would be a nice addition.
Chromis are cool since they school together and are peaceful towards other fish.
Also (although not a fish) a pair of skunk cleaner shrimp look cool too.
However, the damsels limit you a little bit because they can be quite territorial and aggressive. You might consider trying to get them out before adding anything non-aggressive.