I think twotoes is encouraging you to drive during the day because it would really suck to be broken down in the desert at night. It can be VERY desolate, with only two small towns in the 150 miles between Victorville and Las Vegas. Also, you'll be driving over some mountains, and you might have high winds and/or low temps, particularly at night.
If you haven't done it yet, you need to see Vegas at least once in your life. Just be prepared. It can be the tackiest, gaudiest, trashiest, most unfriendly city in North America, but it can also be an absolute blast. Go online and book some concerts, comedy acts, or shows before you go.
Regarding your concern about crime, we had a friend visiting from Japan years ago, and he was scared to death that he'd be murdered here in the USA. After a month in the US, including going to Vegas, though, he was a little disappointed that he never witnessed a single shootout or gun murder. Between slasher movies and what he heard on the news, he assumed that we're still living in the wild west here, shooting up the streets like Yosemite Sam on crack. It's not that bad! Relax and have fun.