Yes, only long term visas do not need a return flight. Very few airlines allow you to cancel a ticket for free and you usually do not get the true value when you cancel. Qatar does let you cancel a ticket and get credit or money back. What exactly are you trying to achieve? Your question is not logical based on the visa type.
So it sounds like I cannot get around the fact that I need to have 400,000B in a Thai bank account based on marriage unless I apply in the US and show proof of assets. But, if I want to stay in Thailand longer than 1 year, I must deposit 400,000B in a Thai bank. Bottom line, I can meet all the requirements, it just depends on if I want to apply in the US or in Thailand. Correct?
In general all of the middle east airlines are good because all the countries are rich and want to show off. I flew Qatar, it was good but more expensive than some. I heard Eva is good too.