Just to circle back, luckily when I exchanged my left-over VND at BKK basement superrich I got a 5 THB coin, used it to call Healthland branch on Srinakarin Road and confirmed 2 x 120 minutes thai massage appointment. Used the airport WIFI and picked up a GRAB from the departure level, cost was 230 THB and took 30 minutes

Had a wonderful time there, 600 THB per person for 2 hours, gave another 100 THB each as tip, facility is clean, nice, and had a private room for the two of us

Had planned to get another GRAB using the facilities free wifi, but the taxi that brought us down asked to bring us back to BKK, that was 200 THB (he ran meter both ways) and paid in cash

Did not get dinged for 700 THB departure tax. Thai Smiles transit at BKK is something less than desirable, had to clear security to get to the departure level, get grilled over by the transit desk staff about not having visited China, and return back down to arrival level to enter Thailand proper - LPQ station refused to issue BKK-PEN boarding pass even thought I had an electronic copy of it from the on-line check-in

So overall < 1900 THB for 2 x 2 hour massage, took under 4 hours total. Had a quick look at the "welcome massage" at the BKK basement, did not look inviting and was priced I believe 450THB per hour