If you want some colour, one of the best tankmates for angelfish are some of the species in the Rosy clade in Hyphessobrycon. Rosy Tetra
and Roberts Tetra
(the latter is one of my favourite tetra) work very well. Bleeding Heart Tetra
is another, though some members here have mentioned trouble with fin nipping the angels. The Serpae Tetra
also is in this clade, but this is a known nipper with angels so never mix these. The Rosy and Roberts should be excellent for some red. Other tetra are Lemon Tetra
, Garnet Tetra, Flame Tetra
I should just mention something about fin nipping. All tetra will resort to this if they are stressed. And one major factor is the number in the shoal; the more there are, the less likely they are to nip, or at least go outside the group to do so. This is one major reason I think that some aquarists have trouble with various tetra, they are not in a large-enough group. As you have the space, I would say no less than 11 or 12 of whatever species.
Another benefit of those species I've suggested is their quiet nature, generally speaking, which does suit sedate angelfish so well. And, they all like darkness, so lots of plants and always have floating plants with any of these fish, and they should remain peaceful.