Dwarf Cichlids (Rams, Apistos, Kribs) are territorial, and most form pair bonds. A male and a female will defend the territory around their nest. I understand some Apistos form harems (1M + 2 or more F). They are not community fish. However, in your large tank there is room for several pairs, as long as the plants, rocks and driftwood make separate areas on the floor of the tank for them to claim. Checkerboard Cichlids are more shy, and might be a bit closer to a community fish than the others. Generally the dwarf Cichlids get along just fine with mid tank and upper level fish, they ignore anything that stays away from their territory.
German Blue and Electric Blue are the same species, and could breed. They will understand their own signals about territory.
Bolivian Rams seem a bit more easy going in some ways, and might make a better group, perhaps 2 pairs or 3 pairs.
Apistos- there are many species, and I do not know how well they understand each others' signals.
Kribs- More aggressive, pushier than the others listed. I would not mix these with shy or gentle schooling fish.
I would not mix species among the dwarf Cichlids.
If you did not have fish that were territorial about the bottom area you could get a really nice school of Cories. Cories do not always get along well with Cichlids, though. Cories do not seem to understand the Cichlids' territory signals and they get into trouble. However, Cories are just fine with other bottom dwellers like Loaches, and are fine with fish that swim higher in the tank.
Other bottom dwellers: A school of Botia striata would be nice in this sized tank, or if you wanted smaller fish, Ambastaia sidthimunki are great.
Schooling fish: You can double the population of Rummy Nose, and still have room to add another school in there.
For slower swimming mid tank fish, how about Pencils, Penguins, or Emperor Tetras? (There are several species of each- just get one species, and enough to make a good school)
For upper level interest you could go with a school of Hatchets (several species, covered tank only) or certain Gouramis. Most are territorial about the upper area, but your tank is large enough you could try several, especially if you could get females. Honey Gouramis- might try a mix of 1-3 males and 2-6 females, Pearls Gouramis- 1M or none, and 2-4 F. Other Gouramis are more aggressive. A single male, or a few females might work. A male Betta or several females might work. Never mix Anabantoids.