Great thread! ^
updates for Thai:
TG upgrades possible are econ>biz, biz>first. First is not offered on all flights.
Miles: TG Royal Orchid Plus miles may be used to upgrade on TG.
Vouchers: One round-trip complimentary upgrade to the next class of service using a paid ticket on qualifying and requalifying for ROP Gold.
Freebies for status ???
Op ups: Posted somewhere in the TG forum, check-in agents are authorised to op-up ROP Gold from econ to biz when flights are more than 90% full in econ. ROP Silver and Star Gold members are have been known to receive op-ups from econ to biz in that order when flights are full in econ.