A big beautiful tank like that...and no catfish? Is that even legal???
I don't have any experience with Geophagus
per se but have kept a grand total of two Gymnogeophagus species, rhabdotus and balzanii. I only mention it because of the huge difference between those two in terms of how bottom-oriented they were in my tanks.
G.balzanii always remained plastered practically on the substrate, never more than a couple inches above; they never fed from the surface or even went after pellets until they had sunk almost to the bottom, regardless if they were kept with other species or only with their own kind. Beautiful fish, but I grew tired of them after a couple years. They simply did not display well in my aquariums, and they were essentially invisible in an outdoor stock tank. They bred fairly well for me, often when I didn't want them to and few of their fry survived if other tankmates were present.
In contrast, G.rhabdotus are much more cosmopolitan in their wanderings. They spend a fair bit of time on the bottom but will also swim freely at all other levels, and don't hesitate to feed on floating foods right at the surface. In an outdoor tank they are as visible as any cichlid ever gets; still fairly cryptic when viewed from above, but at least they can be seen. I still have these and continue to enjoy them. They reproduce like bacteria; you'll likely be using them as feeders before long!
Again, I haven't tried other Gymnos, and no Geos at all. I'm just mentioning this so that you can perhaps research the individual species you are eyeballing to make sure its behaviour suits your desires for the look of your tank, since the behaviour seems to vary widely even between closely related species.