Competiton-style sparring is really a lot different from a "street" fight. In competition, you are both in stances, often waiting for the other person to strike, you are limited on your targets, you can't hit hard enough to stun your opponent, which means that you need to be looking for counter strikes, and, most importantly, your average Joe Drunk isn't going to be a stylized fighter. How you fight, and, subsequently, where you look, will be much different. Generally, though, while sparring i try not to look at anything, but to just point my eyes toward their center of mass and let my peripherial vision do most of the seeing. Remember, though, sparring is mostly for building reflexes, targeting, etc., and for fun. Don't try to relate any more than the general mechanics of it to a real-life fight.