Depending on your budget, the Harlequin Tuskfish is an awesome FOWLR fish that provides an awesome conversation piece. There are also many wrasses that will provide you with tons of activity, loads of color and they are very hardy. The melanurus, is one of my favorites but there are many types of FOWLR wrasses that are available at most LFS. As for damsels....DON'T DO IT!!!! Contrary to popular belief you don't have to cycle a tank with damsels.
Be warry of the panther grouper though they can rapidly hit lengths of 18-20" and should have closer to a 300 gallon aquarium. They will also eat ANYTHING (fish or invert) that they can fit in their mouths. I have also wittnessed them "tasting" there keepers when they reach into the tank. Not that they will take a chuck but it WILL suprise you if it happens.