Picking a prime rib roast is pretty much the same as picking a rib eye steak, you need to look for the marble (evenly distributed small amounts of fat that give the meat a marble look) within the meat. Above is an image of a USDA prime rib roast, you can clearly see the marble affect I am talking about with the white fat woven throughout the meat. This is what you wan to look for when you pick a roast or even a steak. The meat will be twice the price usually, but it will also have more than twice the flavor. The way I see it, I don’t make prime rib often, so when I do I should go all out and pick the best cut of meat. It’s like going to a high end restaurant, if your going to go you might as well try the good stuff on the menu. There is not point in going to a high end restaurant just to get the cheapest thing on the menu, if that is the case you might as well go to a mid level restaurant and get the best thing on their menu.
Above is a “Choice” rib roast (which is not USDA prime), so you can see there is not much of a marble affect. This rib roast will still be tender, but it will not be very flavorful. If you have ever gone to a restaurant that is selling “prime rib” for $13.00 as a weekend special, you are more than likely getting fed “choice” rib roast just marketed as “prime” rib.