Not sure why you are asking about the journey time from the airport paperboy. Usually members are more concerned about the journey time back to the airport to catch their flight home. But to answer your question, it all depends on the time of your arrival. But, as a rule of thumb, IтАЩd allow about 1 hour.

If you are in a hurry, IтАЩd ask the taxi driver to take the expressway (bpai taang duan kr├бp in Thai) and pay the toll charges. I paid 110 baht in toll charges in January 2014 when I used Don Muang Airport. ThatтАЩs slightly higher than the 70 baht I normally pay from Suvarnabhumi Airport.

Have fun!