What are the requirements for obtaining a Multi Entry Tourist Visa for Thailand, especially regarding accommodation and return flights?

Flight in , flight out and flight back in to Thailand again. You MUST prove you need Multi Entry.

In the US you don't get to pick the consulate you apply at,

Look on this pop up, find your state, go to the designated consulate's website, read the requirements for the METV, go to the online eVisa system and apply for it at that consulate

As a rule people show proof of a flight TO thailand from the US and then in 60 days they show a flight to another country with a return to thailand a few days after that. That is more than enough to "meet the need" for an METV to be issued.

For the proof of lodging most people just make a booking for 60 days (which you can cancel after the visa gets approved) and there is no requirement to show where you stay after that first entry.

This is the pop-up you get when you say you're in the US applying for a visa thru the eVisa system;