If you need a car in Vegas use Costco travel. I got a full size for 58.00 for 4 full days from Alamo. Alamo by far had the best rates, followed by Budget. Small size was 41.00.
http://www.carrentalsavers.com/las_vega ... ental.html
http://www.carrentalsavers.com/costco_discounts.html