I've got four fish in my 75g at the moment. Two clowns, a fire angel and a diamond goby.
The clowns don't move around much. One has hosted with my GBTA, so it stays pretty much in that area. The other wanders a bit, but, for the most part, confines itself either to near the other clown or to the completely opposite side of the tank.
The diamond goby ranges the tank, but is, obviously, on the sand the whole time.
The fire angel is the most active of my fish, but it spends it's time moving slowly in and out of the rocks, low in the tank.
Are there any options that will spend more of their time higher in the tank, above the rocks and be more active swimmers, while still being comfortable in a 75g tank?