It's the relationship between the fish and how the fit together as a group that is interesting, more than just gaudy colours. You want fish to fill all zones of the tank with gobies and blennies on the bottom, schooling fish in the middle near the top to draw out the timid fish, and some bigger fish in open areas.
I have seen cases where a large reef tank with 40 fish can appear devoid of fish due to their shyness. Once a school of anthias or chromis is added they know it is safe from predators and they all crawl out of the woodwork. We call these schools of fish "dither fish".
Some Swallowtail angels (Genacanthus sp.) eat anthias feces. They hang out below large schools and wait for the anthias to "make it rain"
Tile Gobies and certain blennies mimic anthias so they can blend in with the crowd for safety when travelling. Normally I wouldn't recommend tile gobies beacuse they don't adapt well to reef tanks, but they are fine with big tanks and look to scale (they put small tanks out of scale with their rapid swimming patterns and larger size 6"). The flashing tile goby is amazing as seen in this not-so-great video.
http://smg.photobucket.com/albums/v221/blackgpgt/?action=view¤t=New90134.flv
Purple tile gobies are even more colourful, but they stick to one vibrant colour.
http://www.getahugetank.com/images/purple_tile.jpg
Garden eels are another one that may work in a big tank like yours, but they need deep sand. You may be able to design a segregated sand area with deeper sand.
http://www.youtube.com/watch?v=rXNjRNbpB9s