I used to live in Phuket in south Thailand 6 years ago, before the Tsunami. I came two years as a tourist and after that I was sold on the place.
I remember the first time I come out from the airport and I thought Bangkok was hot but the humidity in Phuket was really bad the first minute. The second thing I remember was the chaos in the airport taxi queue and as you probably know by now it is controlled by mafia. Not that you will ever notice but there is not many price to pick from when you come without booking a hotel first.
Do not ever book a hotel from the airport and do not go with the busses for free that is going to take you to some travel agency. They will take you to some agency outside Patong beach and you will not be able to get out from there if you not book with them. Well you can if you a lot of money, much more then you would normally.
I did that mistake but I paid with credit card so when I came to town I called them and said sorry I want to cancel and I called my bank and told them what happen.
What you can do instead is book a hotel before you go to Phuket that will always be much cheaper then drop in. The only hotel that is cheaper with drop is the small hotel for back packers that you can find in Lonely Planet for example. But do you really want to live like a backpacker when Phuket has so many nice hotels and bungalows.
The hotel if it is a good Phuket hotel will almost all the time provide a free van from the airport. You do not have to hassle with the van people in the airport and you will get the best price on hotel then you can ever get.