I booked both from the airport and return before I arrived in Thailand.
My arrival flight was late, and it was not an issue, there was someone waiting at… read more the arrivals area with a sign who quickly got the driver for us.
I was a little confused about the return but they arrived at our hotel on time and was a nice smooth transit.
Drivers are friendly, and have water available.
I highly recommend this, it maybe a bit more expensive but you don’t need to worry about a thing. There is no bartering at the airport, or worrying about finding a grab car. They will be there waiting.