...and one of the most scenic routes in the U.S. in my opinion... the Virgin River Canyon abounds in isolation and beauty... Interstate 15 is a typical interstate highway... four lanes and well maintained. Best to try and avoid summer travel though since temperatures easily reach 100 degrees (F).
Plan a stop at Cedar Pocket Rest Area to look around...
The Rand McNally site is great for US journeys. In addition to the other posts, we got a great accommodation deal at the Welcome Centre on the Nevada border.