Great suggestion Sander,
Yes, the last stop going east is Om Nut. I am departing on a Sunday so traffic should be lighter, but I still plan to give myself some extra time.
Dank u well
Just for the heck of it here is another way to get to the airport if you are not in a hurry!
If you left yourself enough time from that Oh Nut (or On Nut-spelling varies) Skytrain stop - there is a #552 bus that stops there for the airport. Opposite side of the road from the Lotus Tesco store. That bus costs only 35 baht! I have waited 55 minutes for that bus and other times I have been lucky and got it in 5 minutes. That bus takes 45 minutes to an hour to reach the little bus station at the airport. Free shuttle to the terminal from there. I would go with the taxi just to be sure this time.