I don't think people are "that" busy or in a rush mode when they are travelling to Las Vegas or other sourthern states... For a couple, saving $200 per flight for +/- 6-12 Hrs of waiting time or even less, should work for holiday fellows.... It still be "WAY WAY WAY" time saving than bus trip...
And, if you can't leave over your office workload or other personal investment affairs, it's sorry for you to go on vacation because you cannot really ENJOY your trip...