Having used the blue Super Shuttle van in the past, multiple stops and being crushed and crammed with wheezy, sneezy, hacking, and gacking patrons from around the valley of the sun is something we decided we would never do again.
That said, for a few extra dollars, my wife and I have decided to utilize Super Shuttle's executive car as a means of traveling to, and from, the airport. Not only is it a more comfortable and spacious ride, but the drivers have been early, and there are no stops prior to reaching our chosen destination.
The drivers we have encountered thus far have been friendly and courteous, as well as conversationalists who keep things light (unlike another source once used while on vacation.) The gratuity is paid for in advance when booking the vehicle, so there is no need to pay according to service rendered or bags handled.
If we were traveling in a large group, for the money and space required, I would recommend the blue shuttle van, otherwise, for the hassle and inconvenience involved, I highly recommend the executive car as a pleasant exchange.