Seems like the best shuttle service for Las Vegas. You can't beat $11 each way (when booked thru your hotel website). You get a reserved time for pick-up and can pinpoint your arrival time within 10 minutes.
The shuttles are clean and the drivers are friendly. They take care of your bags for you and, unlike the cabbies, won't take you on a time-wasting 45 minute circuit around the greater LV area to pad their fare. The airport is only 10 minutes from the Strip.