How can I book a round trip flight while planning to extend my stay in Thailand from 60 to 90 days?

Bangkok, Chiang Mai, Phuket, Buriram and other offices allow you to apply for a 30 day extension when you have 45 days or less left on your current stamp, most other immigration offices let you do it when you have 30 days or less left. There's no reason to wait until your stamp is almost expiring before you apply for the extension because the ADD the 30 days to your current expiration date..

@Tod ********

thank you