In Bangkok you can go directly to the immigration office and get the 30 day extension for 1,900THB….this is contingent on when your plane arrives and you will make there during their normal work hours of M-F minus Holidays….
then definitely go the 6 month METV which you can get 9 months out if it with strategic Border bounces…make sure you get registered wherever you’re staying get the Pink ID Card and yellow house book this will help in opening a bank acct, drivers license etc