just to add: also in BKK you will be met at the gate upon arrival; you will be driven in a golf cart to the transit immigration (conjunction A/B/C/D wings) and escorted further through immigration directy into the domestic departure area (A/B) and into the TG lounge. If you fly Thai Smile Plus, you will anyway have access to the lounge; if cattle, you might get access given the *A ticket on F or you can buy access...

by the way: TG will merge with Thai Smile, so that all the discussions about access for *A status passenger will end and TG will likely also again start to fly with some of their own wide body aircrafts to HKT and CNX