I'd go with bigger schools of the tetras - anything less than 6 isn't really a comfortable grouping IMO.
(actually, I think the fish would prefer 12 of one type over two groups of 6 but hey they don't have the wallet, we do
)
I think you've got room in there for a nice shoal of each - while I wouldn't put them all in right away, I think you could do a dozen of each tetra, plus the apistos and gourami, and have a great looking display. Or - for a really awesome display, 24 of just one of the tetras, plus the other fishes. There's nothing like watching a large shoal of tetras cruising above apistos - the tetras help the apisto's relax, and the apisto's encourage the strong shoaling behavior of the tetras.
Oh, and I think a tank without a bristlenose pleco (ancistris) is like a car without winsheild wipers - you can keep cleaning the glass by hand but its a PITA
(I think the two constants in all my tanks are ancistris and java moss)