We are flying into Vegas for a 3 week road trip in July 2014. We are going to head up to Bryce Canyon, Salt Lake City to Yellowstone, then across to Mount Rushmore and back through Denver. Are we being a bit ambitious with the distance and is there anything we should defiantly not miss seeing on that route. Our three teenage kids will be with us but we have done long road trips in the USA before, just not this distance. Thanks for any help.