This isn't a bad place for transportation. My fiancee and I walked over to the Airport Shuttles when we landed and inquired about transportation to the Mirage. They charge $6 for Strip hotels and $8 for downtown hotels. That isn't a bad deal. Basically, it cost $12 round trip and everything is prepaid, so they can't screw you over. There's a sympathetic sign in the vehicle stating that gratuities are appreciated and that they account for 50% of their salary. What a joke. You'll only get a dollar out of me. Anyways, I recommend that you arrange an earlier pick up from the hotel to the airport, since there may be other stops on the way.
The service is mediocre, but the prices are great. During my previous stays at Vegas, a cab fare would be at around $25...and that's only one way. Don't expect to be pampered with service, but know that the money saved can be used for other things. Have fun.