The "special" races should feel special and be rare in the world. For companions, have a good explanation why they're what they are and why they're there. I think the tiefling camp would work better later on in the game, once our perception is "anchored" in the mundane world of human peasants and Tolkien race common bandits.
Too bad that D&D doesn't treat those races as special. Foe example in the latest D&D adventure up in the far north there is a dragonborn "protector" of a village with no explanation of how he got there all alone.
