MikeS:
I'd be interested. Which non-human races are you permitting?
Anything that's in the Fed up to the TOS movies, including the animated series. So Caitian, Edosian, Deltan, and Efrosian. All the standards, Vulcan, Tellarite, Andorian, and the rest. You could make a case for some TNG-era species, like Betazoid and Bolian, but those would be a really hard sell.