Yes, Dollar has the best rates for booking a rental car in Vegas. What you don't know is that you'll end up waiting in line for about an hour at the rental counter to get a car while people going to every other car company will be off gambling/boozing/eating within minutes.
Was it worth saving $20 total to wait in line at 1:00 am? Hell no. The iPhone and Travelocity had me booked at Avis for the same care (at $20 more per week) in 5 minutes ... and we were on our way. Bottom line, screw Dollar and make up the $20 by gambling for the additional hour.