Something along I-15 south seems to be broken. See this thread. I tried routing to Vegas in live map and it sent me through Reno. However, routing to St. George and then on to Vegas works fine. I'm thinking there is a turn restriction set somewhere along I-15 between SLC and St. George that makes the penalty for driving an extra 600 miles (through Reno) worth it but there isn't a better route to St. George. I am going to try and look for the problem, but I have lost my editing rights south of Provo in the early November editing rights issue and they haven't been restored. Any help that you may want to provide would be appreciated.