A man called Mr. Toom does a service from the airport to your hotel in Pattaya for just 1200 baht including tolls. The car is small but clean and new and the service is fine. I used it the other week - only tiny problem was that I didn't see the driver with my name on a board when I first arrived, but I called the mobile number I was given and she found me 30 seconds later.
I suggest you book well in advance then send another email a couple of days before to re-confirm.
Here's the email address:
toom39@msn.com
For some reason, getting a car back from Pattaya to BKK is much cheaper - there are loads of places that offer it there and there's no need to pay more than 850 baht, plus the tolls which come to 110 baht altogether. I booked mine from a little stall right outside the Lek Hotel on 2nd road, near soi 13.
Bon voyage!