Well ... when you consider that time is money, it might well be better all around to fly over and back, especially if you're traveling anytime between now and October because of the beastly, oppressive, will-to-live sucking H E A T.
The temperature in Las Vegas and the surrounding desert area (which extends all the way to California, which means that you'll encounter these temperatures about an hour outside of LA while on the drive) is a high of 103 F (approx 40 or thereabouts C) with an overnight low of 86 F (approx 34 C or so). I've been there in the month of August when it was 105 F at 2am, so just know that it does not cool off at night. Heaven forbid but if the car breaks down on your drive, you would be stranded in heat that's dangerously high.
When you factor in the time it would take to make the drive, which averages around 5 hours, I would just as soon fly as drive. It's a quick 45 minute hop (once you get past the check in line etc, but still!!), and you're there. If you like, you could rent a car in Vegas, although their public transport has gone through some MAJOR improvements with the monorail system that takes you from one end of the strip to the other in 15 minutes. A day pass for the monorail is just $12, which is cab fare for one ride from the Stratosphere to the Luxor. The monorail is definitely the way to go, especially in the daytime when it's so bleedin' hot.
If you've got a flight for $119, I'd take it and call myself happy :D