I had ED for a while and am still studying Thai after I finished using the visa. I enjoy it. Very satisfying to learn a new language and use it in every day life...and if you get a visa as well....then all good :) Terary is talking about paying a dodgy school to get you the visa without studying. I would NOT advise that...!! You used to be able to get one for ''studying' Muay Thai as well....may still apply. .
Emily if you need to stay longer term after a few tourist visas there is always the ED visa option...that is if you wanted to learn Thai or another language...
Border run, extend, visa run to Laos, extend, border run, extend, visa run to KL, extend, visa run to Myanmar, extend.....well over a year.....then on the 1st of Jan 2019 you get another 2 border runs again....but they will question you eventually....always have 20k baht on your person just in case they ask and check specific Thai consulates before you fly there....they all can be different....
A NON O based entirely on medical reasons, but we are not calling it a medical visa....This reminds me of the OA / retirement Visa argument ;) ;) OK there is no medical visa, but there is a visa specifically for medical reasons....LOL....