John, I was/am in the same boat and was urged by multiple folks to go with this way:

<You come in on a visa exempt or tourist visa entry, get your funds in place then apply for the 90 day Non-O visa inside the country at the immigration office where you live, THEN after you get that you wait and apply for the yearly extension.>

That is my plan at this point. It sounds like it's the easiest. Plus I was a bit worried about the police clearance certificate thing because I have an expunged 27-year-old misdemeanor on my record, and no one could tell me whether the Thais would understand that it was an expunged charge or would just deny me because there was something there on my record. Thus, I will need to go with the Non-O applied for within Thailand because with that route they don't do the police clearance thing.

@Tod ********

Believe me Tod, in this realm, every answer can easily lead to another question or five, and I think you know that. 😁 Okay, well "unlimited entry/exit" is more info on it than I had found, so I thank you for that. I was hoping that was the case. That was one main thing I wanted to know—whether by default it is limited to like only 3 entries a year, or means unlimited entries, or what. They don't spell out these details, which forces newbies to pick things apart and ask follow-up questions. For me it is a very important question because I'm not interested in any one-year arrangement that would lock me into staying in Thailand the whole year (again, this view presupposes a return to relative normalcy next year regarding international travel).

@Luis **********

I think maybe you were aiming that at me? Anyway, thanks for trying to answer. I realize how fluid things still are and will be for a while... I'm really just trying to get an overview of how the multiple entries with an OA work. The only information about it I've seen anywhere simply says "Multiple Entry." That's not enough info, I need to know how many of those I would get a year, how they work, etc.

@James *******

Thanks. Sorry, I should have framed the question slightly differently and more specifically, like this: Assuming things "normalize" next year, will the multiple entry aspect of an OA allow me to easily fly to other countries and return to Thailand? What does the multiple entry aspect normally facilitate? I don't mean land borders, I mean I want to be able to fly to Bali, Vietnam, etc. (once those countries allow it, of course). Just trying to get an overview of the subject of multiple entries and how they work, at least during normal times.