I have three main concepts for alien races and one for human;

The first I mentioned, Kallathani, is a concept I based off of Starcraft; the name is based off the planet Kallathan, which is approximately 3 times larger than the sun, with a variety of races on it. They vary from lightly psionic wildlife, which is generally respected on the planet, to higher level technology beings with strong psionic connections. It's a little bit of a dysfunctional planet government wise; some species were able to advance to space level technology and begin colonization. If I go with that concept, that sub-race is the one I would chose.

The second, the Hydrans, is a very strict hierarchy of entities from the top level command, which from there influences every other lower level. Most hydrans don't have individual thoughts, but are instead bred to be controlled by higher authorities, with some exceptions. It's pretty heavily based off the antagonist species from the game Outwars; but it wouldn't fit all that great in here  (or in many roleplays in a typical role) since a primary part of their culture is the existence of two juggernaughts - massive ships that are basically superdreadnaughts.

The third, and one I think would most fit, is a generally psionic race (levels on average going from 2-4, rarely up to 6) that is extremely proud and still a bit deep in superstition, yet is at the level of going to other planets. It has a caste system based on psionic ability; lower levels (2,3) tend to be at the low end of the spectrum, 4-5 are the higher ups, and 6 and rarely 7 tend to rule/become Archon, the leader of the largest collection of the species that controls a good 90% of the population.
-The homeworld itself is only habitable around the equator; anywhere else is typically too cold. The species itself is humanoid, but with pointy fingers, dark purple scaly skin (usually), very good eyesight and often reflexes, psionic advantages, typically 6-7 feet tall and live up to 200 years. The primary disadvantage is breeding - although both males and females can mate at any point in their lives, actually having a kid happens typically only once and very, very rarely going beyond a single child. Life is accomplished if there's one kid. Psionic abilities carry across bloodlines. That's the very general synopsis of it.

I'm also toying with a colony of remaining humans. It might prove interesting to be the underdog of the "new age" and possibly expand on the human lore side of things.

If I get into this, I'll probably go with the third or fourth option.