Cool do some sandsifters you will be happy, a few that come to mind is of course the Callochromis, Xenotilapia types and or Ophthalmotilapia ventralis a good colony of 6 to 7 would be sweet not all of these are sandsifters but do all get to 5 or 6 inches and will fill the middle up and the sandsifters will do the bottom sand zones..
There are two places here in louisville that have these available so you could do a 2 hour road trip and pick them up for cheap..
And of course their is the Buscheri, Lelupi, and a few others that you could do but these get super aggressive and Trets are nasty fishes as well i have a large male in my 120gal predator tank i would throw one in unless you throw like 4 in so that they mess with each other..