celestar, do tell about Thai business class! I noticed that the price difference from coach is not so great. And many of the flights I am looking at (intra-aisa) only had business and coach seats available (no first). I guess the biggest benefit is that Coach on Thai only gets 50% mileage on UA, where as business gives you full credit(???).

Upgrades on Thai are usually from Coach to Business. It's very rare from Business to First because First Class are only available on their 747 flights long-haul, and Business Class hardly ever fills up.

Thai tends to upgrade coach to Business on fully booked flights. You may not ask at time of check-in - they are all done at the descretion of the airport station manager, or they will 'exchange' your coach borading pass with a Business Class one at the gate. But from experience, flights that you may be upgraded are from Singapore or Hong Kong to Bangkok.

Thai's Business Class are dismal in comparison to other airlines (just ask Dutchboy). Most of their 747's only have 36 inch pitch, no legrest, no personal inflight entertainment (except a Sony Videoman with outdated movies). Their 777-200 aircraft have got to be the worst aircraft confirgured around .... 2-4-2 for Business Class and 3-4-3 for Coach! Even at 50" seat pitch for this aircraft, the seats are VERY uncomfortable. But the 777-300 fares slightly better. The Airbus A330 also have HARD seats in Business, and meals are quite - well, pathetic. For some apparent reason, Thai has a newly configured 747-400 series aircraft with fully flat seats in First Class and 50" seat pitch in Business. This is shown on airline CRS as 747 aircraft and the other tight pitch seats aircraft as 744. So if your travel agent thinks that 747 means an old 747-200 aircraft, they're wrong. Currently these 'newer' aircrafts fly between BKK and PAR, and BKK and LAX. And the odd HKG flight.

As for unexpected bonuses check the HP Forum!!!