Thanks for the advice fellas. Sounds like the bag tag could work. There's a OW transit desk here:

https://www.oneworld.com/airports-de...ngkok-thailand

Failing that, it might have to be the Novotel that's been recommended. We've spent many an involuntary hour at BKK over the years since it opened, and the public areas don't inspire us. Food in that Thai food court is good, but not worth two or three hours there.