Since the tank is quite tall you can get a lot of difference in movement, I know they don't look like much but they add a nice movement to the surface and that's Hatchetfish. They shoal in nice groups, but mostly stay near the surface. Angelfish will float around pretty much everywhere, but they prefer midwater. Just make sure the Hachetfish you buy are big enough to deal with them. On the bottom Corys, definitely, you will not regret them, they add a lot of energy to the bottom of the tank. Also a pelagic, more full-bodied tetra species like Moenkhausia, or Gymnocorymbus (less so) species, would add a bit of movement to the center. Finally a little bit of a showy fish down the bottom since Corys don't tend to be the most colourful would be BR's, GBR's, Apistos, or even something a bit rarer, if you didn't mind about biotoping, like Badis Badis, although they aren't the most colourful, just interesting.
Just watch Hatchets, they jump!
Tek oot.