After years of doing nothing much in Bangkok, I've recently done a few flights in a short space of time.
Oman Air - a good level of service, new planes and ok prices (can be expensive at times). Bkk to Muscat; Muscat to Colombo; Kathmandu to Muscat. All 8/10.
Ethiad - the worst food I've ever tasted on a plane, but new planes and efficient. I wouldn't go out of my way to fly them, but their prices are sometimes good. Muscat to Abu Dhabi; Abu Dhabi to London, and back again (6 hour delay at Heathrow...). 7/10
Cathy Pacific - ok service (Oman Air were better), new plane, decent price. Colombo to Bangkok (it was a red-eye flight, and the staff seemed more interested in sleeping than doing their job; very empty plane; 777 with maybe 40 people on board). 7/10 (if I'm being kind). I expected better.
Qatar Airlines - very cheap (half the price of Oman Air and Ethiad even though I had to travel an extra hour in the wrong direction to get to Dohar first; packed plane), excellent new planes, very good staff, good food. Very good indeed. Muscat to Dohar; Dohar to Bangkok. 9/10 (the food could have been better). I was vert pleasantly surprised.
Now to the expected problem - Thai Airlines... I recently flew from Bkk to Kathmandu, and the options were multiple stops (Air Asia, crappy Indian airlines), Nepal Airlines at 9,000 baht or Thai Air at 12,200 baht. In a rash moment, mainly because you can't book online with Nepal Airlines, I booked with Thai Air.
Thai Air - new 777, great entertainment, comfortable seats, very good staff, easy check-in, the plane took off ontime and landed 40 minutes early, the food was the nicest I can ever remember eating on a plane. I was shocked, don't know what to say... 10/10. Well done Thai, the price wasn't that bad (yes, it was the most expensive of the 5 options I found by 25%), but the entire experience was excellent. Shocked!