Thai Visas For Us Citizens

[Asiaphile]

I'm so sorry to post this, as it's probably redundant, but I have browsed through many posts here and can't seem to find the answer.

What are the visa options for US citizens who do not have any special qualifications (Thai spouse, employer, retirement age, etc.)?

As I understand it, I can fly into Thailand and be given a 30-day, non-extendable entry permit.

OR, I can apply for a tourist visa at a Thai embassy or consulate before visiting Thailand - I hear this is generally best done in ones home country?

I guess I can get a 60-day single or double-entry tourist visa, which can be extended another 30 days (each entry). So, for example, if I got a 60-day, double entry visa, I could go to Thailand, extend my stay within Thailand (at an immigration office) 30 days, leave Thailand within 90 days of arrival, then come back and do the same thing for a total of about 180 days.

Is this correct?

More importantly, what other options do I have? Can I somehow get a 1-year, multiple-entry visa, good for 90 days each entry? That's what I'd really like. Would this be an "O" visa?

Many thanks!