I use Presidential every time i go to Las Vegas & I have yet to have anything but great experiences. Their drivers are on time, friendly & the vehicles are all clean and well maintained. The pick-up email reminder is great, especially in Vegas when you can forget a whole lot more than what time your driver is coming the next morning :)
I always book the round trip SUV service & have the driver stop at a liquor store on the way to the hotel so i can buy a few bottles of champagne & beer. I have never had a driver complain about stopping, they are always great. Sometimes on the way back to the airport we get them to go through the Inn&Out Burger drive-thru since we don't have Inn&Out in Canada & love it so much. Once again, no issues from the driver, especially if we buy him lunch :p
All in all, a great company that I would recommend to anyone looking for a reliable transport service in Vegas!