Los Angeles is only 272 miles from Las Vegas, with the journey taking between four and five hours on one of the many private coaches that run trips between the two cities. The scheduled Greyhound bus service takes longer, around five to seven hours, but tickets only cost $60 as of 2010.
You can choose from a number of private companies that either run organized day trips to Las Vegas from Los Angeles or just provide a coach service and allow you to entertain yourself upon arrival. LuxBus America run round trips from Los Angeles to Las Vegas for $99, as of 2010, although some may find that day trips are not practical with the company's departure and arrival times.
Plenty of Los Angeles tours to Las Vegas don't just drop you in Sin City and leave you to have your own fun. Starline Tours, more famous for their trips around the city of Los Angeles, runs organized tours to Las Vegas that also take you out to the Grand Canyon and the Hoover Dam. If you're choosing to head five hours across the desert to Vegas, you should take the opportunity to visit this natural phenomenon.