You see them a lot more on the multi loop races like Laughlin, Primm, Parker, Las Vegas Cup, etc.. The loops range in distance from 1.5 miles to 130 miles, so you see the cars a lot.
The point to point races like the Baja 1000 or Vegas to Reno are the true endurance, adventure races, other races are better spectator races. Look at Dakar, 17 days, 8000 miles of racing, a very crappy spectator race. I was told Dakar was also the second most watched motor race ( behind Indy) it the world. Buy the videos or go to Laughlin to see the cars, build your own to experience it.