IMO, Smallfolk can model halflings, gnomes and even dwarves or kobolds with ease; you don't need more than one elven race (please, no!); technically orcs and ogres fill the same niche (I would cut orcs). What to add, though? A smaller, centaur race modeled off deer; Beastfolk, like the awakened spirit idea posted above...
OR don't add another race (The simple list of Human, Elf, Ogre, Smallfolk appeals to me). Add a section or sidebar to each of the races giving examples of how to manipulate the races to create the campaign world a particular group wants to play in. Since race is little more than a bit of fluff, an array of base stats, a list of skills, and a special ability it should be simple enough to give some advice/examples on how to switch things around to get the array of races that the group wants. Ogres don't work for you? Change this and this and you've got orcs. Human too generic? Change these things for the Men of the Black Isles. You get my point.
I would much rather have fewer detailed out options and more encouragement, examples, and ideas to manipulate and modify the game to make it what I (as player or DM) want it to be. I feel the same way about traditions.
