Ah good
Geophagus are best kept as groups the bigger the better in most cases - the species is kind of split into three complexes - Surinimensis, Braziliensis and Stiendachnari. If you like groups of cichlids these could be for you
I have a group of 4 Winemilleri which are part of the Surinimensis group and I have them with a mouth brooding Severum, Chocolate Cichlid and a Threadfin Acara and Im growing up a Thorichtys sp.Mixteco Gold and a Nicaraguan with them all of which get along fine the young Nicaraguan is the biggest problem I have.
Along with Geophagus you also get Satanoperca which I touched on earlier there are a number of species in there again all best kept as groups of 4 or more. As they are quite gregarious and in lower numbers start to get problematic. They are found in largish numbers in the wild.
Also there are a number of related species to Geophagus that do well in groups, like Cupids which are really nice. You also get Guianacaras the Bandit Cichlid and Gymnogeophagus, but Gymnogeophagus needs quite a specialist set up as they need 3 months or so of cool water each year.
If you like Severums make sure you have a look around there are some great specimens around at the moment Heros Notatus is really nice but equally a nice big Green is always a good fish. Rotkiels are a favorite of mine, though never had chance to keep them. I only keep singletons of things apart from the Geos as breeding fish can be a problem and they get along pretty well by them selves.
Neons would get eaten by the Severum pretty quickly I had Lemons with my Severus for a while but my Chocolate cichlid started eating them and he is only 6 inches so you might be better off with a larger species like Columbian or a fast species like Bleeding Hearts. You could also look at Hemiodus species as well. I have a school of Annostomus Ternetzi but there are a couple of other nice headstanders around like spotted or marbled just be careful with the larger species as they can be problematic.
If you like groups of cichlids a group of Surinimensis Geophagus with a group of Cupid Cichlids could look incredible
A large shoal of Bleeding Heart Tetras and some spotted Headstanders?
Wills