An afternoon or evening of watching racing should be about racing, not commentators. The best announcers or commentators in sports are the ones who interject their opinions and insights when needed, not to excess. John Madden has always been the best football commentator I ever saw because he always leaves you wanting more, not less, from him.
When I occasionally watch it I find it incredulous that anyone can watch that channel without muting it, its that bad. Everything they do is to excess and there are just too many of them. It seems as if not only are they trying to outshine each other, but they are also trying to outshine the races you are watching.
Good commentators would simply keep viewers updated on possible biases they see at tracks, and perhaps helpful tidbits like who is first time gelded or first time lasix. To talk nonstop is extremely annoying, and usually counterproductive. I've also heard them speak about how a horse looks in the post parade. This is fine but often useless if you don't know how the horse NORMALLY looks. To just say he or she seems sweated up is not real helpful when delivered as a negative if the horse is usually hot in the paddock or post parade. By the same token, if they say a horse who looks calm and collected(delivered as a postive) its not always great if the horse is usally showing more life.
The best way to help educated and non eduacted viewers alike is to simply give an overview of each race and perhaps how the track has been playing. They beat things to death and often in a theatric manner that overshadows the race. As far as selections go, why be forced to make selections on every race all day? Any sharp player is going to pass races or have races that they deem as just too hard to analyze in their opinion. Opinions on races mean a lot more when only delivered if you feel that you actually have one, instead of just throwing darts and looking for kudos when one happens to land ok.