@Nguyen ****************
I have a return ticket that departs long after my initial Thailand stay (because I will come and go over to other countries, returning to Thailand in the spring) so the argument could be made that I don't have flight bookings yet to make certain that I am leaving Thailand within the terms of the 1 month visa I will get. But as with many things, this is up to the discretion of the Immigration officer in BKK (and also airline staff at every check-in along the way). In fact having paper-work permitting one to enter any country is never 100% certain. It is the first step, we can still be denied entry. The final gatekeeper is when we present ourselves with our papers to Thai Immigration when we land.
I used AXA.